UNIT-I INTRODUCTION. Introduction to Computer Early days people use fingers for computing purpose. As years go, the computing needs also grew. This leads.

UNIT-I

INTRODUCTION

Introduction to Computer

• Early days people use fingers for computing purpose.

• As years go, the computing needs also grew. This leads to the invention of calculators and computers.

• The term computer is derived from the word compute, it means to calculate.

Definition

• Computer is an electronic device. It accepts data, process the data and gives the desired output.

COMPUTERINPUT OUTPUT

Basic functions or operations

• Input

• Processing

• Output

• Storing

• Controlling

Basic operations (Cont)

• Input

It is the process of getting the data from the user or from somewhere else into the computer to process.

• Processing

It is the process of converting the input to output.


• Output

It is the outcome or result of the process.

• Storing

It is the process of saving the data. so that it can be retrieved whenever needed.


• Controlling

It is the process of directing the sequence in which the operations to be performed.

Applications of computer:

• Business

• Industry

• Home

• Education

• Printing & publishing

• Entertainment etc.,

CHARACTERISTICS OF COMPUTER

• Speed

• Accuracy

• Diligence

• Versatility

• Resource sharing

• Storage

CHARACTERISTICS OF COMPUTER (cont)

• SpeedThe computer process the data

extremely fast. (i.e.) in millions (1,000,000) of instructions and even more per second. A computer can perform a huge task in few sec where a human being may take hours or even days to complete the same task.

• Accuracy

The degree of accuracy of computer is very high and every calculation is performed with the same accuracy. The accuracy level is determined on the basis of design of computer. The errors in computer are due to human and inaccurate data.



• Diligence A computer is free from tiredness,

lack of concentration etc. It can work for hours without creating any error. If millions of calculations are to be performed, a computer will perform every calculation with the same accuracy. Due to this capability it overpowers human being in routine type of work.


• Versatility

It means the capacity to perform completely different type of work. For example At a moment a computer can be used to draft a letter. Next moment it can be used print a document or play a music file etc.,


• Resource sharing

In organizations the computers are connected to form a network. The resources such as printers, scanner, plotters are connected to the network and it can be shared by the computers in the network.


• Storage

Computers are capable of storing huge amount of data and it can be located and retrieved very quickly. It uses storage devices such as hard disk to store huge amount of data.

Evolution of Computers

• Abacus The first calculating device called

ABACUS was developed by the Egyptian and Chinese people. It consisted of sticks in horizontal positions on which were inserted sets of beads. It has a number of horizontal bars each having ten beads. Horizontal bars represent units, tens, hundreds, etc.

Evolution of Computers (Cont)

• Napier’s bones English mathematician John Napier

built a mechanical device for the purpose of multiplication in 1617 A D. The device was known as Napier’s bones.

• Slide Rule This machine could perform

operations like addition, subtraction, multiplication, and division. It was widely used in Europe in 16th century.


• Pascal's Machine

Blaise Pascal developed a mechanical calculating machine called Pascal’s calculating machine. It could add and subtract. The machine consisted of wheels, gears and cylinders.

• Leibniz’s Machine

The Pascal’s calculating machine can perform addition and subtraction but it could not perform multiply and division. Leibniz built a mechanical device that could both multiply and divide.


• Babbage’s Analytical Engine In the year 1823 that a famous

English man Charles Babbage built a mechanical machine to do complex mathematical calculations. It was called difference engine. Later he developed a general-purpose calculating machine called analytical engine. Charles Babbage is called the father of computer.


• Electronic Calculator The electronic calculator used in

1960’s was run with electron tubes, Later it was replaced with transistors and as a result the size of calculators became too small. It can compute all kinds of mathematical computations. Some calculators have in-built programs to perform some complicated calculations.

Generations of Computers (Cont)

First Generation Computers:• These computers were vacuum tube

based machines.• They used magnetic drums for memory.• Input were fed into the computer using

Punched cards• The size of these computers were very

large and it produce more heat.• They lacked in versatility and speed.• They were more expensive.

First Generation Computer

Generations of Computers (Cont)Second Generation Computers

• Here the Transistor replaced the bulky vacuum tubes.

• Transistors are smaller than vacuum tubes and have higher operating speed.

• Thus the size of the computer got reduced considerably.

• Manufacturing cost was also very low.

2nd generation

Generations of Computers (Cont)Third Generation Computers

• These computers were based on Integrated Circuits (ICs) Technology.

• A single IC has many transistors, registers and capacitors built on a single thin slice of silicon.

• So that the size of the computer got further reduced.

• These Computers were small in size, low cost, large memory and processing speed is very high.

3rd generation

Generations of Computers (Cont)Fourth Generation Computers • It uses large scale Integrated Circuits (LSIC)

built on a single silicon chip called microprocessors .

• Later very large scale Integrated Circuits (VLSIC) replaced LSICs

• These computers are called microcomputers. • Thus the size of the computer got reduced. • The personal computer (PC) are comes under

the Fourth Generation.

Generations of Computers (Cont)Fifth Generation Computer

• The speed is extremely high in fifth generation computer.

• The concept of Artificial intelligence has been introduced to allow the computer to take its own decision.

• It is still in a developmental stage .

5th generation

Classification of Computer

• Microcomputer

• Mini Computer

• Mainframes

• Supercomputer

Classification of Computer

Microcomputer SupercomputerMini Computer Mainframes

Computer

Desktop

N/W Servers

Laptops Smart phones

Classification of Computer (Cont)

Microcomputer

• Microcomputer is at the lowest end of the computer range in terms of speed and storage capacity.

Eg: Desktop, Laptop, Tablet PC, Smart Phones.


Mini Computer

• This is designed to support more than one user at a time.

• It possesses large storage capacity and operates at a higher speed.

• This type of computer is generally used for processing large volume of data in an organisation.

• Eg:Servers in Local Area Networks (LAN).


Mainframes

• They operate at very high speed, having very large storage capacity and can handle the work load of many users.

• They are generally used in centralised databases.

Classification of Computer (Cont)Supercomputer • They are the fastest and most expensive

machines.• They have high processing speed

compared to other computers. • They have also multiprocessing technique.• Supercomputers are mainly being used

for whether forecasting, biomedical research, and other areas of science and technology


• The computers can also classified based on the hardware design as follows

–Analog computer.–Digital computer.–Hybrid computer.

CONTROL

MEMORY

ALU

OUTPUTINPUT

Basic organisation of computer


• INPUT– The input unit is used to information or

instruction to the computer.– It accept the information or instruction from

user or from some where else.– Convert it to a computer understandable form

and send it to the computer.

Eg:Keyboard,mouse,Joystick,MICR, etc,.

Basic organisation of computer (cont)

• CENTRAL PROCESSING UNIT (CPU)– It is the heart of the computer.– It performs all operations.– It contains the followings

• CONTROL UNIT• ALU• MEMORY


• CONTROL UNIT– It controls all other units in the computer.– It directs the sequence in which operations to

be performed.– It also controls the flow of data between

various units.


• ARITHMETIC & LOGICAL UNIT

– It performs all arithmetic & logical operations.– i.e. arithmetic operations like addition,

subtraction, multiplication, division etc,. And logical operations like AND,OR,NOT etc,.


• MEMORY UNIT– Place for holding the information.– Types

• Primary• Secondary

– Primary memory is used to store temporary data.Eg:RAM,ROM etc,.

– Secondary memory is used to store information permanently. Eg:Hard disk.


• OUTPUT– The output unit is used to display the result of

the process.

Eg:Monitor,printer,speakers, etc,.

Components of Computers

• Hardware

The physical components present in the computer.

• Software

It is a collection of programs and it can perform some operaions.

Components Present inside the cabinet

• Motherboard

• Processor

• SMPS

• Disk drives

• RAM & ROM etc,.

Types of Memory

MEMORY

SECONDARYPRIMARY

RANDOM ACCESSSEQ.ACESS

• Primary Memory:

It is used to store data temporary.

RAM• Random Access Memory

• It is possible to randomly select and use any location of the memory.

• It is a volatile memories i.e. It loose their content when the power is switched off

ROM• Read Only Memory

• The data in the ROM is permanent .

• It is a non-volatile memories i.e. It does not loose their content when the power is switched off .

• Programmable Read Only Memory

• It is supplied in blank by the manufacturer.

• It is possible to store program in PROM chip.

• Once the programmes are written it cannot be changed and remain even if power is switched off.

PROM

• Erasable Programmable Read Only Memory.

• Information stored in EPROM can be erased by exposing the chip in ultraviolet light and it is reprogrammed using a special programming facility.

EPROM

• Electrically Erasable Programmable Read Only Memory.

• Information stored in EEPROM can be erased by applying some voltage.

EEPROM

• Secondary Memory:

It is used to store data permanently

• TYPES: sequential access , random access

Sequential Access

Magnetic Tape:

• Magnetic tapes are used by large computers like mainframe computers where large volume of data is stored for a longer time.

• The cost of storing data in tapes is inexpensive.

• Tapes consist of magnetic materials that store data permanently.

Random AccessHard Disk:• It uses circular disk ,coated with magnetic

material called platters. • It rotates with very high speed inside the drive. • Data is stored on both the surface of the disk.• Each disk consists of a number of invisible

concentric circles called tracks. • The information stored in a disk can be read

many times without affecting the stored data.

Magnetic Hard Disk Mechanism

Random Access (cont)

Optical disk

• It uses a circular plastic disk coated with aluminium or silver storing data.

• The data are stored in the circular tracks.

• Laser beam is used for storing and retrieve data from the disk

INPUT OUTPUT DEVICES

• Input Devices

Input devices are necessary to convert our information or data in to a form which can be understood by the computer.

• Eg: Keyboard, Mouse, MICR,OMR,OCR.

Keyboard

• This is the standard input device.• The layout of keyboard is just like the

traditional typewriter of the type QWERTY.• It also contains some extra command

keys and function keys. • The computer can recognise the electrical

signals corresponding to the correct key combination and processing is done accordingly

Mouse

• Mouse is an input device.

• When the mouse is moved across a flat surface the screen pointer is also moved in the direction of mouse movement.

• It is easier to move the cursor through a mouse

Magnetic Ink Character Recognition (MICR)

• This is widely used by banks to process large volumes of cheques and drafts.

• Cheques are put inside the MICR.

• As they enter the reading unit ,the magnetic field which causes the read head to recognise the character of the cheques.

Optical Mark Reader (OMR):

• This technique is used in objective type tests and the answer are marked by darkening a square or circular space by pencil or pen.

• These answer sheets are directly fed to a computer for grading where OMR is used.

Optical Character Recognition (OCR):

- It is used to recognize any printed character.

- This characters are compared with patterns stored inside the computer.

- Whichever pattern is matched is called a character read.

- Patterns that cannot be identified are rejected. OCRs are expensive though better the MICR.

Visual Display Unit

• The most popular output device is the Visual Display Unit (VDU).

• It is also called the monitor.

• Monitor is used to display the input data and to receive massages from the computer.

• It can be color or monochrome.

Printer

• It is an important output device which can be used to get a printed copy of the processed text or result on paper.

• printers are classified as impact and non-impact printers.

Number System

• Number Base B => B symbols

–Base 16(Hexa):0, 1,……9, A ,…, E, F

–Base 10 (Decimal): 0, 1, 2,……, 7, 8, 9

–Base 8(Octal): 0, 1, 2, 3, 4, 5, 6, 7

–Base 2 (Binary): 0, 1

Number System (cont)

• Number representation:

• d31d30 ... d2d1d0 is a 32 digit number

• value = d31x B31 + d30 x B30 + ... + d2 x B2 + d1 x B1 + d0 x B0

Decimal Numbers: Base 10

• Base or Radix is 10

• Digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9

• Example:

41210 = 4x102 + 1x101 + 2x100

= 400 + 10 +2 = 412

Binary Numbers: Base 2


• Digits: 0, 1

• Example:

1012 = 1x22 + 0x21 + 1x20

= 4 + 0 +1 = 5

Octal Numbers: Base 8


• Digits: 0, 1, 2, 3, 4, 5, 6, 7

• Example:

1238 = 1x82 + 2x81 + 3x80

= 64 + 16 +3

= 83

Hexadecimal Numbers: Base 16• Digits: 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F:

–A 10–B 11–C 12–D 13–E 14–F 15

• Example:

1216 = 1x161 + 2x160

= 16 +2 = 18

Conversions

Decimal to Base N Base N to Decimal

Successive Division by N

(Remainder Method)

Multiplication with power of N

Conversion of 2510 to Binary

2 25

2 12 -1

2 6 - 0

2 3 - 0

1 - 1

2510=110012

• Binary to decimal conversion

11001 1X20 = 1 0X21 = 0 0X22 = 0 1X23 = 8 1X24 = 16

2510

Conversion of 12510 to Octal

8 125

8 15 - 5

1 - 7

12510=1758

• Octal to decimal conversion

175 5X80 = 5 7X81 = 56 1X82 = 64

125

1758 = 12510

Conversion of 8410 to Octal

8 84

8 10 - 4

1 - 2

8410=1248


124 4X80 = 4 2X81 = 16 1X82 = 64

84

1248 = 8410

Conversion of 45010 to Hexadecimal

16 450

16 28 - 2

1 - 12

45010=1C216

• Hexa to decimal conversion

1C2 2X160 = 2 12X161 = 192 1X162 = 256

450

1C216 = 45010

Conversion of 38510 to Hexadecimal

16 385

16 24 - 1

1 - 8

38510=18116

• Hexa to decimal conversion

181 1X160 = 1 8X161 = 128 1X162 = 256

385

18116 = 38510

Other Conversions

• BINARYOCTAL

• BINARYHEXA

• OCTALHEXA etc,.

• BINARYOCTAL• OCTAL – BASE 8 = 23

• 3 DIGIT BINARY NUMBER

Example:110012 OCTAL

11 001

011 001

3 1

110012=318


1 110 011

001 110 011

1 6 3

11100112=1638

• BINARYHEXA• HEXA – BASE 16 = 24

• 4 DIGIT BINARY NUMBER

Example:110012 HEXA

1 1001

0001 1001

1 9

110012=1916


1 110 011

001 110 011

1 6 3

11100112=1638

• OCTALHEXA

• OCTALBINARYHEXA

Example:318 HEXA

3 1

011 001

0001 1001

1 9

318=1916

• HEXA OCTAL

• Example: 1BD OCTAL

1 B D

0001 1011 1101

000 110 111 101

0 6 7 5

1BD = 6758

Conversion of 25.12510 to Binary

2 25

2 12 -1

2 6 - 0

2 3 - 0

1 - 1

2510=110012

0.125 X 2 = 0.250

0.250 X 2 = 0.5

0.5 X 2 = 1.0

25.12510 = 11001.0012

• Binary to decimal conversion11001.001

1X2-3 = 0.125 0X2-2 = 0 0X2-1 = 0 1X20 = 1 0X21 = 0 0X22 = 0 1X23 = 8 1X24 = 16

25.12510

Conversion of 84.25010 to Octal

8 84

8 10 - 4

1 - 2

8410=1248

0.250 X 8 = 2.000

25.12310 = 124.28


124.2

2X8-1 = 0.25

4X80 = 1

2X81 = 0

1X82 = 0

25.25010

UNIT-I INTRODUCTION. Introduction to Computer Early days people use fingers for computing purpose. As years go, the computing needs also grew. This leads.

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