354 33 Powerpoint-slides Ch1

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MICROPROCESSORS -

INTRODUCTION AND EVOLUTION

© Oxford University Press 2013



Introduction• Microprocessor is an electronic chip that functions as

the central processing unit (CPU) of a computer

• In other words, we can call microprocessor as the heartof any computer system.

• Some may call the microprocessors as the brain of thecomputers.

• The microprocessor based systems with limitedresources are called as microcomputers.

• Now-a-days microprocessors are found in almost allelectronic machines and appliances in its different form




Introduction• Some common devices using microprocessors are

computer printers, automobiles, washing machines,microwave ovens, mobile phones, fax machines, Xeroxmachines and advanced instruments like radar,satellites, flights etc.,

• Any middle class house-hold will have about a dozensmicroprocessor in different forms inside variousappliances.

• The recent developments in electronic industry and the

large scale integration of devices has led to rapid costreduction and more and more application ofmicroprocessors and its derivatives.




Introduction• Almost all microprocessors use the basic concept of

“stored program execution”.

• By this concept, programs or the instructions to be

executed by the microprocessor are stored sequentially

in memory locations.

• The microprocessor or the processor in general will

fetch the instructions one after the other and execute

them it in its arithmetic and logic unit.




Introduction• A microprocessor can be programmed to do any task

that can be written and programmed by the user.

• So, in order to work with the microprocessor, it isnecessary for the user to know about the internal

resources and features of the microprocessor.• The programmers must also understand the

instructions that a microprocessor can support.

• Every microprocessor will have its own associated set

of instructions that it supports and this list is given byall the microprocessor manufacturers





Introduction• The instruction set for microprocessors is given in two

formsa) one in mnemonic which is comparatively easy tounderstand

b) the other in binary machine code which themicroprocessor really works upon and difficult to understandby us.

• Programs are written using mnemonics called theassembly level language and then they are convertedinto binary machine level language.

• This conversion can be done manually or using anapplication called assembler.




Introduction• In general, the programs are written by the user for

a microprocessor to work with real world data.

• These data are available in many forms and arefrom many sources.

• To give this data to the microprocessor, themicroprocessor based systems need some inputinterfacing circuits and some electronic processingcircuits.

• These circuits include data converters and ports




Introduction• After processing the real world data, the output from

the microprocessor must be taken out to give to final

end effect instrument or circuits.

• This again needs interfacing circuits and ports.

• So, a microprocessor based system will need a set of

memory units, set of interfacing circuits for inputs and

a set of interfacing circuits for outputs




Introduction• All circuits put together along with microprocessor are

called as microcomputer system.

• The physical components of the microcomputer system

are in general called as hardware.

• The program which makes this hardware useful is

called as software.




Basic terms• Chip

a) A chip or an integrated circuit is a small, thin

piece of silicon with the required circuit and

transistors etched on it to perform a particularfunction.

b) Simpler processors might consist of a few

thousand transistors etched onto a silicon base just

a few millimeters square.




Basic terms• Bit

a) A bit means a single binary digit.

b) Also, the bit is the fundamental storage unit ofcomputer memory. In binary, bit can have only two

values, 0 or 1, whereas a decimal digit can have 10values, represented by symbols 0 through 9.

• Bit Size

The bit size of a microprocessor refers to the number

of bits that can be processed simultaneously by thebasic arithmetic circuits of the microprocessor.




Basic terms• Word

A number of bits grouped together for processing is

called as word. In microprocessors, the word in

general refers to the basic data size or bit size that can

processed by the ALU of the processor. 16-bit binary

number is called a word in a 16-bit processor.

• Memory word

The number of bits that can be stored in a register ofmemory element is called a memory word. Mostly all

memory units use 8-bits as their memory word.




Basic terms• Byte

An 8-bit word is referred to as a byte

• Nibble

A 4-bit word is referred to as a nibble

• Kilobyte

A collection of 1024 bytes is called a kilobyte (210bytes)

•

MegabyteA collection of 1024 Kbytes is called a megabyte (220bytes)




Basic terms• RAM or R/W memory

a) Random Access Memory or Read/ Write memory isthe type of semiconductor memory in which a particularmemory location can be erased and written with a new

data at any time.b) These memory units are volatile, which means thatthe content of the memory is erased when the power tothe chip is disrupted.

c) The access of the individual memory location can bedone randomly. In microprocessors, the RAM is used tostore data.




Basic terms• DRAM

a) Dynamic Random Access Memory is a

semiconductor memory in which the stored

contents need to be refreshed repeatedly at aboutthousands of times per second.

b) Without refreshing, the stored data will be lost.

c) These memory chips are preferred in a computer

system because it is economical although slower.






Basic terms• Arithmetic and Logic Unit (ALU)

a) ALU is a digital circuit present in the microprocessor

to do performs arithmetic and logic operations on

digital data.

b) The typical operations performed by the ALU are

addition, subtraction, Logical AND, logical OR and

comparison of binary data.

c) Generally, the functions of the ALU of amicroprocessor will decide the functionality that can

be performed by the processor.




Basic terms• Microcontroller

Microcontroller is a chip that includes microprocessor,memory and I/O signal ports. Microcontrollers can becalled as single chip microcomputers.

• MicrocomputerThe system formed by interfacing microprocessor withmemory, and I/O devices to work with the requiredprogram is called microcomputer.

• Bus

The bus in a microprocessor system refers to a groupof wires or signals having a common functionality




Basic terms• System Bus

The System bus is a group of signals used for

communication between the microprocessor and

peripherals.

• Firmware

Software written for a microprocessor application

without provision for changes. These are stored into

permanent storage or ROM of the computer system.




Basic terms• Input device

The devices that are used for giving data to themicrocomputer system are called as input devices.Usually keyboard and mouse are the input devices

through which data and instructions are given tocomputer.

• Output device

The devices that are used for getting data out from

the microprocessor or microcomputer system arecalled as output devices. A display screen, printer anddisplays are the common output devices.






Basic terms• Von-Neumann Architecture

The architecture in which the same memory is used

for storing the program as well as data.

•

Harvard ArchitectureThe architecture in which the program and data are

stored in two separate memory units.

• CISC Processor

“Complex Instruction Set Computer”, is a processor

architecture that supports many number of machine

language instructions.




Basic terms• RISC processor

a) “Reduced Instruction Set Architecture”, is aprocessor architecture that supports limited or smallnumber of machine language instructions.

b) RISC processors are expected to execute theprograms faster than CISC processors.

• High level Language

a) A computer programming language in whichprograms are written without the knowledge of the

processor in which the program will be executed.b) BASIC, FORTRAN, C, PASCAL and JAVA are theexamples of high level languages.




Basic terms• Assembly Language

a) A programming language written using the

mnemonics or the instruction set of a particular

microprocessor.

b) Assembly language programming is microprocessor

specific.

c) It cannot be easily understood like a high level

language program.d) But these are easier than machine language

program.




Basic terms• Machine Language

a) The binary code programs that are specific to the

processor and can be directly executed by the

processor.

b) The machine language is the lowest level program

and cannot be easily understood.

• Assembler

A computer application program that converts theassembly language program into machine level

language program.




Basic terms• Compiler

A computer program that converts the high level

language program into machine level language

program.

• Interpreter

a) A computer program that reads the high level or

assembly level program one line at time and converts

that into machine level program.b) Compiler and assembler can function only on the

entire program in a file.




Basic terms• Algorithm

a) A sequence of operations or instructions that

defines how to solve a problem using a computer or

microcomputer.

b) An algorithm must be definite and follow a clear

instruction flow without any ambiguity and must have

a definite starting and end point.




Basic terms• BIOS

a) Basic Input/ Output System is a set of program

that handles the input and output functions and

interacts with the hardware directly.

b) A new hardware installed must be provided

with the corresponding BIOS routines.




Basic terms• Clock

a) The circuit in the computer that generates the

sequence of evenly spaced pulses to synchronize the

activities of the processor and its peripherals.

b) The clock speed determines the speed of the

operation of the computer.

c) The computer with a high frequency clock works

faster. Normally the clock frequency is in the range ofMega Hertz, MHz or Giga Hertz, GHz.






Basic terms• Operating System

a) The program that controls the entire computer and itsresources and enables users to access the computer and itsresources.

b) Under the control of the operating system, the computer

recognizes and obeys commands typed by the user.c) In addition, the operating system provides built-inroutines that allow the user’s program to perform input-output operations without specifying the exact hardwareconfiguration of the computer.

d) In low level microprocessor based systems, the programthat controls the hardware is called as monitor routines ormonitor software.




Types of Processors• Two types of processors are manufactured

a) the microprocessor

b) the microcontroller

• The general purpose microprocessors give the

computers all the necessary computing power.• These microprocessors need additional circuitry

elements such as memory devices, I/O ports to connect

the input and output devices.

• All microprocessor based systems need two types of

memories – RAM and ROM.




Microcontrollers• The microcontrollers are the microprocessors designed

especially for control applications.

• Microcontrollers contain memory units and I/O ports

inside a chip in addition to the CPU part.

•Microcontrollers are otherwise called as embeddedcontrollers are generally used to control and operate

smart machines.

• Some of the machines using microcontrollers are

microwave ovens, washing machines, sewing machines,automobile ignition systems, computer printers and fax

machines etc.




Microcontrollers• Out of 100 processor chips manufactured, 99 are

embedded processors and remaining 1 processor

alone goes into general computers.

• Lots of semiconductor companies are in the market of

microcontrollers and any application developmentengineer is flooded with the variety of

microcontrollers as the choice.




Microprocessor based

system• The system consists of CPU, memory and I/O ports

• The interfacing of the processor with the other parts

of the microcomputer system needs three busarchitecture.

• The three buses are

a) data bus,

b) address bus

c) control bus






Microprocessor based system•

An address bus of 8 bits 28

different memory locations.• Similarly, the 16-bit address bus can address 216

different addresses. Its address ranges from 0000H to

FFFFH.

• The higher the number of lines of address bus is, themore the locations the processor is able to manage.




Microprocessor based system•

A control bus is needed for proper data transferbetween the processor and other peripherals.

• The control bus basically consists of signals like selectingthe proper memory or I/O device from the address;signal to indicate the direction of data transfer; and thesignal to synchronize data transfer between slowdevices.




Origin of Microprocessor•

The breakthrough in transistor technology led to theintroduction of minicomputers of the 1960s and the

personal computer revolution of the 1970s.

• Intel was the first MPU producer and has been holding a

large share in the world market of this product.• Microprocessors evolution is categorized into five

generations

– first, second, third, fourth, and fifth generations.




First Generation (1971-73)•

The microprocessors that were introduced in 1971 to1972 were referred to as the first generation systems.

• Intel Corporation introduced 4-bit 4004 at 108 kHz, the

first microprocessor in 1971, co-developed by Busicom,

a Japanese manufacturer of calculators.• In 1972, Intel made the 8-bit 8008 and 8080

microprocessors




Second Generation (1974-78)• Very large-scale integration (VLSI) lead to chips which

had speeds up to hundreds of millions of switching persecond.

• The second generation marked the beginning of veryefficient 8 – bit microprocessors.

• Some of the popular processors were Motorola’s 6800and 6809 and Intel’s 8085, Zilog’s Z80.

• The distinction between the first and second generationdevices was primarily the use of newer semiconductortechnology to fabricate the chips.

• They were manufactured using NMOS technology.




Third Generation (1979-80)• Introduced in 1978, dominated by Intel’s 8086 and the

Zilog Z8000, which were 16-bit processors withminicomputer-like performance, have 16-bit arithmeticand pipelined instruction processing.

• Transistor counts about 250,000.

• Motorola’s MC68020, incorporated an on-chip cache forthe first time and the depth of the pipeline increased tofive or more stages.

• HMOS - speed-power-product of HMOS is four timesbetter than that of NMOS.

• HMOS can accommodate twice the circuit densitycompared to NMOS.




Fourth Generation (1981-95)•

Designs with more than a million transistors in apackage.

• 32 bits microprocessors introduced – Intel 80386 and

Motorola 68020/68030.

• Fabricated using low-power version of the HMOStechnology called HCMOS.




Fifth Generation (1995 till date)•

Employed decoupled super scalar processing.• Chips carry on-chip functionalities and improvements

in the speed of memory and I/O devices

• Design surpassed 10 million transistors per chip.

• Introduction of 64-bit processors

• Intel leads the show with Pentium, Celeron and dual

and quad core processors working with up to 3.5GHz

speed.




General Purpose Processors - Comparison




•

Microprocessors can be classified based on theirpurpose, architecture, specifications and applications.

• Based on the size of the data that the microprocessor

can handle, they are classified as 4-bit, 8-bit, 16-bit, 32-

bit and 64-bit microprocessors.• Based on the application of the processors, they are

classified as i) General purpose processors, ii)

Microcontrollers and iii) Special purpose processors.

Classification of Microprocessors




General Purpose Processors•

General purpose processors are those which are used ingeneral computer system integration and can be used by

the programmer for any application.

• Common microprocessor such as Intel 8085 to Intel

Pentium processors are examples of general purposeprocessors.

• Microcontrollers are the microprocessor chips with in

built hardware for the memory and ports.

• These chips are can be programmed by the user for any

generic control applications.




Special Purpose Processors•

Special purpose processors are designed specifically tohandle special functions required for an application.

• The digital signal processors are examples for the special

purpose processors and these have special instructions

to handle signal processing.• The Application Specific Integrated Circuits (ASIC) chips

are also the examples of this category of

microprocessors.




Classification of microprocessors•

Based on the architecture and hardware of theprocessors, they are classified as

a)RISC processors,

b)CISC processors,

c)VLIW processors and

d)Superscalar processors.

• Reduced Instruction Set Architecture’, is a processor

architecture that supports limited or small number ofmachine language instructions.




Classification of microprocessors• RISC processors can execute the programs faster than

CISC processors.

• CISC – Complex Instruction Set Computing architecture

a) CISC processors have about 70 to few hundred

instructions and are easier to program.b) CISC processors are slower and more expensive thanRISC processors.

c) Very Long Instruction Word (VLIW) processors have

instruction composed of many machine operationswhich can be executed in parallel.




Classification of microprocessors•

This is achieved by many functional units operating inparallel.

• It has large number of registers and instruction level

parallelism is achieved.

• Superscalar processors are using complex hardware toachieve parallelism.

• It is possible to have overlapping of execution of

instructions in order to increase the speed of execution.




Memory Unit – An Introduction• Memory unit is the integral part of any microcomputer

system and its primary purpose is to hold program anddata.

• The major design goal of memory unit is to allow it tooperate at a speed close to that of the processor.

• The cost factor inhibits the design of entire memory unitwith single technology that guarantees high speed.

• In order to seek a trade-off between the cost andoperating speed, a memory system is usually designedwith different technologies such as solid state, magneticand optical.




Memory Unit – An Introduction•

A microcomputer memory can be logicallydivided into four groups

a) Processor memory/ register

b) Cache memory

c) Primary or Main Memory

d) Secondary memory




Memory Unit – An Introduction• Processor Memory refers to a set of CPU registers.

Processor registers are the first set of storage deviceavailable for the programmers to store any data.

• But they are generally few in number up to about

few tens to hundreds.• As these registers are available within the processor,

they are the fastest memory registers.

• The main disadvantage is the cost involved which

forces to restrict the number to very few registers offew bytes.





Cache memory is the fastest external memory to theprocessor and they are placed close to the processor.

• The instructions to be executed are placed in cache

memory for access by the processor. These are in few

kilobytes in size.• These are semiconductor RAMs and are volatile.

• The processor will fetch the next instruction from the

cache memory and if the instruction is not in cache, it

will refer to primary memory.





Primary memory is the storage area from which all theprograms are executed.

• All the programs and corresponding data must be within

primary memory prior to execution.

• The size of primary memory is much larger compared toprocessor memory and cache memory but its operating

speed is slower than them.

• The primary memory in a system varies from few

Kilobytes to about 1 Megabyte.







Stored information in a magnetic tape or magnetic diskis not lost when the power is turned off.

• Therefore these storage devices are called nonvolatile

memories.




Primary Memory - Classification•

Primary memory normally includes ROM (Read OnlyMemory) and RAM (Random Access Memory).

• Microprocessor based systems have at least one RAM

and ROM chips in it.

• Information stored in semiconductor random accessmemories RAM will be lost if the power is turned off.

• This property is known as volatility and hence, RAMs

are usually called volatile memories.• ROM is a nonvolatile memory.




Primary Memory - Classification




Primary Memory - Classification• As the name implies, a ROM permits only a read access.

There are many kinds of this category.

• Mask Programmable ROMS are custom made for thecustomer and their contents are programmed by themanufacturer.

• Since they are mass produced, they are inexpensive. Thecustomer can not erase or program it afterwards.

• Programmable ROMs are the devices which can beprogrammed by the user at the user’s place or field.

• The main disadvantage of PROMs is that they cannot beerased and reprogrammed






EPROM• Electrically Erasable PROMs (EEPROMs) or Electrically

Alterable ROMs (EAROMs) allow the users to erase its

contents by electrical means and also reprogramming by

electrical signals.

•EEPROMs are different from RAMs in the electricalsignal required to erase and program. EEPROMs require

a higher voltage for erasing and programming other

than the normal 5V supply.




Static RAM• In a semiconductor memory constructed using bipolar

transistors, the information is stored in the form ofvoltage levels in flip-flops.

• Such memories are called static RAMs because storedinformation remains constant for some period of time.

• Static RAM maintains information in active circuits,power is required even when the chip is inactive orstandby mode.

• Hence, static RAMs require large power supplies.

• Also each static RAM cell is about four times larger inarea than an equivalent dynamic cell.




Dynamic RAM• Semiconductor memories designed using MOS

transistors, the information is held in the form of

electrical charges in capacitors.

• the stored charge has the tendency of get leaked away.

These memories are referred to as dynamic RAMs.• In order to prevent any information loss, dynamic RAMS

have to be refreshed at regular intervals. Refreshing

means boosting the signal level and writing it back.

• This activity is performed using a hardware unit called

“refresh logic”.




Differences




Input and Output Devices• The input/output or I/O section allows the computer to

take in data from the outside world or send data to the

outside world.

• Peripherals such as keyboards, video display terminals,

printers, and modems are connected to the I/O section.• These allow the user and the computer to communicate

with each other.

• The actual physical devices used to interface the

computer buses to external systems are often called

ports.




Function of I/O Ports• An input port allows data from a keyboard, an A/D

converter, or some other source to be read into the

computer under control of the CPU.

• An output port is used to send data from the computer

to peripheral devices, such as a video display terminal, aprinter, or a D/A converter.




Function of I/O Ports• Simplest type of input or output port is just a set of

parallel D flip-flops.

• If they are being used as an input port, the D inputs are

connected to the external device, and the Q outputs are

connected to the data bus which can take the data tothe CPU.

• Data will then be transferred to the data bus when they

are enabled by a control signal from the CPU.




Function of I/O Ports• In a system, where they are being used as an output

port, the D inputs of the latches are connected to the

data bus, and the Q outputs are connected to some

external device.

•Data sent out on the data bus by the CPU will betransferred to the external device when the latches are

enabled by a control signal from the CPU.




Input Devices• Input devices include typewriter-like keyboards; hand-

held devices such as the mouse, trackball, joystick, andspecial pen with pressure-sensitive pad; andmicrophones.

• The simplest input device is a switch.

• Input devices can also be sensors that provideinformation about their environment temperature,pressure, and so forth to a computer.

• Another direct-entry mechanism is the optical laserscanner (e.g., scanners used with point-of-sale terminalsin retail stores) that can read bar-coded data or opticalcharacter fonts.




Output Devices• An output is any device through which the user can

receive the results from the computer.

• The output can be any display which can be changing

fast or hard copies print out. Some other forms of

output are sounds and alarms.• The simplest output devices used in almost all

microprocessor based systems or computer systems are

the LEDs or the seven segment LED displays and LCD

displays.




Output Devices• The advanced video display terminals (either cathode-

ray tubes or liquid crystal displays), ink-jet and laser

printers, are the common output devices nowadays.

• Some output devices can be used to directly control

machineries.• Some devices, such as display terminals with touch

screen, may provide both input and output.

• Modems and other network interface cards can also be

called as output devices as they enable the transmission

and reception of data between computers.




Technological Improvements• Technology improvements are taking place fast in the

microprocessor, microcomputer and personal computer

systems.

• The technical and research improvements in the field of

microprocessor technology is listed below. – Increase in data bus / address bus width. The

processing capability of the microprocessor can be

drastically improved by increasing data size




Technological Improvements•

Increase in speeda) As the data to be processed by the

microprocessors and computers increased in volume,

it became a necessity to increase the speed of the

processor.

b) By high speed processors, the user can get the

results faster even with the large data volumes.




Technological Improvements• Reduction in size and increase in capability

a) The trend in microprocessor technology is to includelarge amount of peripherals such as memory and I/Oports within a single chip.

b) Microcontrollers are manufactured by allsemiconductor manufacturers in this aspect.

c) Development in the processing of large scaleintegration has lead to small chips of microprocessorswith large built in peripherals.

d) We have now processors with large amount of flashmemory available in the market.




Technological Improvements• Development of external peripherals

a) The use of computers in all the fields have resulted in

the development of many fast and advanced peripheral

devices to be interfaced with the microprocessor.

b) For example, applications of microprocessors inmedical field has resulted in many handheld electronic

devices with the specialized input sensors and output

printers etc.

c) The faster peripherals can increase the speed of

processor execution and a good user interface.




Technological Improvements• Increase in memory size and speed

a) The developments in the Integrated circuit

technology have lead to developments in the reduction

of the memory size and the increase in memory speed.

b) This reduces the memory access time of theprocessor and so will result in the higher speed of

execution.

c) Also more amount of memory per unit area is

possible




Technological Improvements• The microprocessors are largely used in handheld

devices operated from the battery source.

• This has resulted in the research towards reduction of

power consumption in the microprocessor chips.

• As power consumption is reduced, the devices can workfor more time with one full charge of batteries.

• There are many devices operating at 3.3V are even

lower and have low power consumption.

S




Summary• Microprocessor is an electronic circuit that functions as

the central processing unit (CPU) of a computer,

providing computational control.

• The microprocessor is the controlling element in a

computer system.• The microprocessor performs data transfers, does

simple arithmetic and logic operations, and makes

simple decisions

S




Summary• The basic operation of the microprocessor is to fetch

instructions stored in the memory and execute them

one y one in sequence.

• Microprocessors are used in almost all advanced

electronic systems• Microcontrollers are advanced forms of microprocessors

with memory and ports present within the chip

S




Summary• A microcomputer system is made y interfacing memory

and I/O devices to a microprocessor

• Microprocessor evolution is classified into five

generations

• The processors that are currently in use belong to thefifth generation

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