1 fundamentals of computer system

8/3/2019 1 Fundamentals of Computer System

1/11

FUNDAMENTAL COMPUTER SYSTEM

Computer is defined in the Oxford dictionary as An automatic electronic apparatus for makingcalculations or controlling operations that are expressible in numerical or logical terms.

The term Computer is used to describe a device made up of a combination of electronic andelectromechanical (part electronic and part mechanical) components. Basically a computer

system is a combination of following six elements:(1) Hardware (2) Software (3) Data / Information

(4) Procedures 5) people (6) communications

A Computer is a programmable computing electronic machine, which takes inputs from various

input devices, processes the inputs with the help of Central Processing Unit, store if necessary inthe memory part and provide the output through various output devices. That is computer can

retrieve, process, store, and distribute data and information as and when desired.

Von Neumann architecture

Most of todays computer designs are based on concepts developed by John von Neumannreferred to as the von Neumann architecture.

Figure shows the basic structure of a conventional Von Neumann machine.

Address Interconnection Data and instruction Interconnection

Data and Control

Information Interconnection

Figure 1: Structure of a computer

The key features of a von Neumann machine, The hardware of the von Neumann machine consist of

(i) A CPU that includes an ALU and CU.

(ii) A main memory system(iii) An input/output system

Main

Memory

Operational

Registers

Arithmetic &logic unit

Input / Output

System

Control

Unit


2/11

The Von Neumann machi

stored in. the same mem

and data on separatedifficult as they were ent

Each location of the m

independently.

Execution of instructions i

(unless explicitly altered by t

A von Neumann machine has(CU). This feature/constraint

architectures have been suggeste

General Computer Architectu

Input Devices:

It accepts or reads the list It converts these instructi It supplies the convert

processing.

Apart from keyboard (foinserting pictures, audio

frequency, etc.

Central Processing Unit:

The CPU is the brain ofexecuting programs, the

memory, input and outpu

e used stored program concept, i.e., the prog

ry unit. The computers prior to this idea used t

emories. Entering and modifying these prored manually by setting switches and plugging

ain memory of von Neumann machine c

n Von Neumann machine is carried out in a s

he program itself) from one instruction to the n

nly a single path between the main memoryis referred to as von Neumann bottleneck

d for modem computers.

e

of instruction and data from the outside world.

on and data in computer acceptable form.

d instructions and data to the computer sy

r direct entry) some other output devices are al, video, touch, temperature, pressure, force,

a computer. Its primary function is to execute

CPU also controls the operation of all other co

t devices.

am and data are

o store programs

rams were veryand unplugging.

n be addressed

quential fashion

xt.

and control unit. Several other

stem for further

so developed forcurrent, voltage,

rograms. Beside

ponents such as


3/11

Under its control, programs and data are stored in the memory and displayed on the CRTscreen or printed on the printer.

The CPU of a small computer is a microprocessor. The CPU of a large computer containsa number of microprocessors and other ICs on one or more circuit boards. Each

microprocessor in a large CPU performs a specific task.

The major sections of a CPU are:

(i) Arithmetic and Logic Unit (ALU)

The function of an ALU is to perform arithmetic and logic operations such as addition,subtraction, multiplication, and division; AND, OR, NOT (complement) and

EXCLUSIVE OR operations.

All calculations are performed and all comparisons (decisions ) are made in theALU.

It also performs increment, decrement, shift and clear operations.(ii) Control Unit (CU)

The CU generates timing and control signals necessary for the execution of instructions. It provides status, control and timing signals necessary for the operation of other parts of

the CUP, memory and I/O devices. That is the CU acts as a central nervous system for

the other components of the computer.

It controls the entire operation of a computer. It is actually the control section of the CPU,which acts as the brain of a computer.

(iii) Accumulator, General and Special Purpose Registers

The accumulatoris a register, which holds one of the operands prior to the execution ofan instruction and receives result of the most arithmetic and logical operations. Some

CPU contain a single accumulator, other contain several accumulators. General purpose registers store data and intermediate results during the execution of a

program. They are accessible to programmers through instructions if they are working inan assembly language.

Special purpose registers are not accessible to users. The computer uses them fordifferent purposes during program execution. (Ex.- Index registers, instruction register,

program counter, stack pointer, etc.)

Memory:

Memory in a computer system is required for storage and subsequent retrieval of theinstructions and data. It stores program, data, results or any other kind of information.

The following levels of memory are present in a digital computer:Internal processor memories (CPU Register): these consist of the small set of high speed

registers which are internal to a processor and are used as temporary locations where

actual processing is done.

Cache memory: it is placed in between the CPU and the main memory. It is much faster

than the main memory; access time about 10 nano seconds. It stores instructions and data,

which are to be immediately executed. It stores or catches some of the content of the


4/11

main memory, which is currently in use of the processor. It is much costlier than the

main memory and hence its capacity is kept much less than that of the main memory.

Primary or Main memory: it is mainly based on integrated circuits and accessed directly

by the processor (CPU). It stores programs along with data, which are to be executed. It

also stores necessary programs of system software, which are required to execute theusers program. Semiconductor memory chips RAMs (random access memory

temporary sort of memory) and more permanent memory chips - ROM (read onlymemory) are used as main memory.

Secondary or Auxiliary memory: it stores operating system, data files, compilers,

assemblers, application programs etc. The CPU does not read information directly from

the secondary memory. The programs and data if needed by the CUP are first transferredfrom the secondary memory to the primary memory. Then the CPU reads them from the

primary memory. The results are also stores in the secondary memory. It is a mass

storage memory. It is slow but cheap. It is permanent memory. Hard disk, floppy disk,CD-ROM, Magnetic tape & disk are the examples.

Output Devices:

The output devices receive results and other information from the computer and providethem to users.

The computer sends information to an output device in the binary form. An output deviceconverts it into a suitable form convenient to users such as printed form, display on ascreen, voice output, etc.

The commonly used output devices are CRT (Cathode Ray Tube) or Monitor, printers,plotters, microfilm, speaker, telephone system etc.

Complied by: Dr. Alok BansalReferences: Computer fundamentals by B. Ram and by P. K. Sinha

Management Information System by James A. OBrien.


5/11

Brief History of Computers

Ever since the mankind started to carry on trade with other people, they felt the need of a system

to keep track of the numbers. They used different ways to do so and started evolving tools. The

earlier computing devices such as Abacus were created to serve the same purpose. Let us have a

look at the major milestones, which led to present day computers.

3000 B.C. The Abacus a rudimentary first computing device developed.

A.D. 700-900 Europeans started using Hindu-Arabic Math.

1600 Hindu-Arabic Math becomes popular in Europe.

1614 John Napier introduced Logarithms.

1642 Blaise Pascal, a French Mathematician and experimental Physicist, built the first

mechanical digital calculator, Pascaline that could perform addition and subtraction on

whole numbers.

1822 Charles Babbage, Professor of Mathematics at Cambridge University and considered as

"Father of computers", invented difference engine with mechanical memory to store

results.

1840s Augusta Ada, The first Programmer" suggested binary data storage rather than the

decimal.

1850s George Boole, a self taught English Mathematician, realized that complex mathematical

problems could be solved by reducing them to a series of affirmatively or negatively

answered questions. The binary system of 1s for positive answers and 0's for negative

ones could thus be implemented. This theory of Boolean logic became fundamental to thedesign of computer circuitry.

1880s Dr. Herman Hollerith, a Statistician, was employed by the Census Bureau, which was

falling far behind in its ability to provide census reports. To find a solution to the census

problem, Hollerith developed a punched card that would contain data coded in form ofpunched holes. Hollerith then built tabulating equipment that could read the cards and

process the data.

1939 The first prototype electronic computer was conceived by Dr. John Vincent Atanasoff.a Professor of Physics and Mathematics at Iowa State College. Atanasoff teamed up with

Clifford Berry, his graduate assistant and began to build the first electronic computer.

They called it the "Atanasoff-Berry Computer" or ABC. The ABC used vacuum tubesfor storage and arithmetic-logic function. The ABC was designed for the special purpose

of solving systems of simultaneous equations.

1940s Von Neumann presented a paper outlining the stored program concept.

1944 Aiken built the Mark I, the first automatic, sequence-controlled calculator: used bymilitary to compute ballistics data.


6/11

1947 Mauchly and Eckert built ENIAC (ENLAC is an acronym for Electronic Numeric

Integrator And Calculator). It was a second general-purpose electronic digital computer.

1949 Englishman Maurice V. Wilkes of Cambridge built EDSAC (Electronic Delayed Storage

Automatic Computer), the first stored program computer.

1949 Mauchly. Eckert and Von Neumann built EDVAC (Electronic Discrete Variable Auto-

matic Computer), the second stored program computer.

1949 At Harvard, An Wang, founder of Wang Laboratories developed magnetic-corememories.

1949 Jay Forrester at MIT organized magnetic-core memory to be more efficient.

1950 Turing built the ACE (Automatic Computing Engine), which can be considered the first

programmable digital computer.

1950s Read Admiral (Retd.) Grace Hopper developed UNIVAC I Compiler.

1951 Mauchly and Eckert built the first computer, designed and sold commercially -UNIVAC

I (Universal Automatic Computer).

1957 Backus who was one of a group of IBM (International Business Machines) Engineers

developed FORTRAN (FORmula Translation Language).

1959 Kilby and Noyce developed and perfected the integrated circuit, to be used in later

computers.

1959 Hopper developed the COBOL (Common Business Oriented Language) programming

language.

1960s Gene Amdahl designed IBM System/360 series of Mainframe computers, the firstgeneral purpose digital computers to use integrated circuits.

1963 Olsen with Digital Equipment Corporation produced the PDP-1 (Program Data

Processor), the first mini computer.

1965 Dr. John Kemeny, a Mathematics Professor at Dartmouth and his colleague. Dr. ThomasKurtz, developed the Computer language BASIC (Beginner's All-purpose Symbolic

Instruction Code).

1970 Intel created a memory chip that could store a kilobit of information. A kilobit translates

roughly into 25 five-letter words. Another innovation at Intel came from Ted Hoff, whohas integrated circuit by compressing twelve chips into four. The arithmetic and logic

functions of several chips could be contained on one chip, called microprocessor. Hoffs

microprocessor was called the Intel 4004 ("forty-oh-four').

1975 H. Edward Roberts, an electrical engineer who is now generally known as the "Father ofthe Micro Computer" designed the first Micro Computer.

1976 Seymour Cray's CRAY-1 Super Computer was delivered to Los Alamos Scientific

Laboratory in New Mexico.

1977 Stephen Wozniak, the technical expert and Steven Jobs designed and built the first Apple

Micro Computer.

1980s Lower-cost computer systems-Personal computers intended for home use were

produced. New program products introduced.


7/11

Generations of Computers

Evolution of modern computer is commonly considered in terms of Generations of computers.

These are the steps in computer technology, which provides a framework for the growth of thecomputer industry. Each new generation has made the following changes in computer

characteristics:

1. Increase in speed.

2. Increase in storage capacity.

3. Increase in reliability.

4. Reduction in system cost.Let us consider some of the characteristics of each generation.

First Generation (1942-1955): Vacuum Tube Technology

1. The 1st Generation of computers relied on vacuum tubes to store and process information.

2. Vacuum tube was a fragile glass device that could control and amplify electronic signals.

These tubes consumed a great deal of power, were short-lived, and generated a grate deal

of heat.

3. 1st Generation computers had extremely limited memory and processing capabilities and

were used for very limited scientific and engineering work.

4. Punched cards used for feeding information.

5. Punched cards and paper used for getting results.

6. Magnetic tapes were used for external storage.7. Oriented towards batch processing, where the entire machine is dedicated to a particular job

until completed.

8. Human operators had to set switches.

9. Development of machine language and assembly language.

10. Typical Computers: UNIVAC I, IBM 650, BURROUGHS 220.

Second Generation (1955-1964): Transistors

1. The transistors invented by Bell Telephone Laboratories in 1948, formed the basis for thesecond generation of computers. In the 2nd Generation transistors replaced vacuum tubes as

the devices for storing and processing information.

2. Transistors were much more stable and reliable than vacuum tubes, they generated lessheat, and they consumed less power. Through use of the transistor, these computers were

much faster, more reliable and more versatile than first generation computers. However,

each transistor had to be individually made and wired into a printed circuit board, a slow

tedious process.3. The enhanced processing power and memory of 2nd Generation computers enabled them to

be used more widely for scientific work and for such business tasks as automating payroll

and billing.4. Punched cards and magnetic tape used for input of data.

5. Punched cards and paper used for output.

6. Magnetic core storage i.e. magnetic tape used for external storage.

7. Oriented towards far more versatile types of applications in which multiple users werecapable of using the machine concurrently.

8. Human operators handled punched cards.

9. Development of high-level languages FORTRAN, COBOL, BASIC. PL/I and others.

10. Typical computers: IBM 1400 Series and 7000 series. Control Data 3600, General Electric635 and Honeywell 200.


8/11

Third Generation (1964-1975): Integrated CircuitsThird generation of computers included significant advances in machine hardware along with

heavy emphasis on software, the computer programs, designed to make the machine work.These included special operating systems, which provided capabilities for automatic

proceeding from one job to the next without human intervention and for multiprogramming,

which made it possible for a machine to perform several jobs concurrently.A summary of main features of this generation of computers is as follows:

1. The 3rd Generation computers relied on Integrated Circuits (IC) for storing and processinginformation.

2. Integrated Circuits (Microelectronic) were made by printing hundreds and later thousandsof tiny transistors on small silicon chips. These devices were called semiconductors.

3. 3rd

Gen Computer technology introduced software that could be used by people without

extensive technical training, making it possible for computers to enlarge their role inbusiness.

4. Monitors and keyboards were introduced for data input and output.

5. Punched cards began losing their prominence as the input or output device.6. Magnetic disks used for external storage.7. Designed around sophisticated operating systems capable of handling several jobs

concurrently.8. A concept of computer "families" was introduced.

9. More high-level language including RPG (Report Program Generator) and PASCAL were

developed. Heavy emphasis was laid on applications-oriented languages-FORTRAN and

COBOL.10. Typical computers: IBM System/360.

Fourth Generation (1975-Present): Very Large Scale Integrated Circuits1. The 4th Gen computers use very large-scale integrated circuits (VLSICs) for storing and

processing information.

2. VLSICs are packed with as many as 200000 to over 3 million circuits per chip. Further

miniaturization in which complete circuits are reduced to virtually microscopic sizes.Hundreds of circuits may be placed on a chip of the size of a pinhead. These developments

were followed by creation of microprocessors. Based on microprocessor, many of the

intelligent features are easier to use.3. Costs have fallen to the point where desktop computers are inexpensive and widely

available for use in business and every day life.

4. Further refinement of input and output devices.5. Introduction of microcomputers.

6. Magnetic disks became the primary means of external storage.

7. Further sophistication of operating systems capable of virtual storage, in which the machinecan operate as if its main storage were several times its actual size.

8. The beginning of broad use of special software for managing large databases.

9. Fourth generation languages emerged and application software for microcomputers became

popular.10. Typical Computers: IBM System/370, Burroughs B7700 and HP3000.

Fifth Generation (Present and Future): Artificial Intelligence

The future may hold the following possibilities:

1. Conventional computers are processes information serially, one instruction at a time. In the

future, more computers will use parallel processing and massively parallel processing to


9/11

blend voice, images, and

intelligence and intricate m

2. Supercomputers capable ointelligence, computers t

computer hardware. ArtifiScience that is involvedhuman imagination or intel

when the term was coinedthen, researchers have use

Computer Science in an athat do tasks which no mac

An example of AI in acti

package that attempts to especialists so that package

3. For the foreseeable future,

alliance with humanity. Thbrain in matters involvi

superiority in matters requi

Major trends in computer syste

Complied by: Dr. Alok Bansal

References: Computer fund IT Today by S.

Management In

massive pools of data from divers sources

athematical models.

f billions of calculations per second and advaat can "think" and "reason" and further m

ial Intelligence (AI) may be described as a bra

ith using computers to solve problems thatligence. The public first became aware of this d

as the theme for a conference held at Dartmouconcepts from disciplines such as Linguistics,

tempt to learn, how to prepare programs or chine has ever automatically done before.

n is the use of expert systems. An expert syst

ncode the knowledge and decision rules estabusers can call on this expertise in making their

the computers will continue to be intelligence

is alliance would combine the current superiorg creativity, judgement and intuition with

ring processing, speed, accuracy and tireless att

m capabilities.

mentals by B. Ram and by P. K. Sinhaaiswal

ormation System by K. C. Laudon and J. P. La

And by James A. OBrien

, using artificial

nced in artificialiniaturization of

nch of Computer

ppear to requireiscipline in 1956

h College. SincePsychology and

onstruct systems

em is a software

lished by humanwn decisions.

amplifiers in an

ity of the humanthe computer's

ntion to detail.

don


10/11

APPLICATIONS OF COMPUTER1. Computer Application in Business:-

Cost & Budgetary Control Stock control & Sales Distribution Mathematical Models & O.R. Pay Roll & Personal Records Banking Insurance & Stock broking Help to Management

2. Comp. Appl. in Project Management:- General & Clerical Planning & Decision Models Information Oriented Simulation (Suture Scenario)

3. Comp. Appl. in Personal & Administration:- Manpower Planning H R D Selection & Recruitment Compensations & Benefits Industrial Relations & Grievance Handling Establishment of Personnel Records Collective Bargaining Training Group Insurance Bill Inventory System Administration

4. Comp. Appl. in Accounting & Finance:- Invoicing, Sales Ledgers & Statements Stock Control & evaluation. Pay Roll, Pay-Slips, Tax Returns. Purchase Ledger & Sales Credit Control Budgetary Control Cost Accounting Assets Registers Hire Purchase Records Financial Ratios P & L Statements Balance Sheet Ledger Day Book

5. Comp. Appl. in Material Management:- Material Planning / Specification Requirements determination Inventory Management Purchasing Production Scheduling Stocking Allocation Distribution

6. Comp. Appl. in Production Plan. & Control:- Reduce WIP & Buffer Stocks Reduce in Material wastage Decrease of idle machine time & increase output

by proper scheduling

Better coordination between depts. Optimization of product mix

7. Computer Application in Marketing:- Sales & Customer Analysis Promotion & Advertising New Product Development Sales & Forecasting Product Planning Product Pricing Expenditure Control

8. Comp. Appl. in Science & Technology:- Scientific Research Industrial Application Weather Forecasting Space Techniques Communication Local & Public Utilities Simulation Artificial Intelligence Defense Application (Military)

9.Computer Application in Multimedia: - Education & Research Medical Science Morphing Video Conferencing Marketing Business Presentations Virtual reality Image Processing Internet Entertainment

10. Other Application of Computer: - In Offices In Book Publications In D.T.P. & Graphics In Data Analysis & Database management In Education In Medical field In Govt. etc.


11/11

1 fundamentals of computer system

Documents