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Computer Introduction


The word "computer" comes from the word "compute",which means,"to calculate".Hence,people usually consider a computer to be a calculating device that can perform arithmetic operations at high speed.We can define a computer as a device that operates upon data; data can be either numerical,non-numerical or a mixture of both.Nowdays 80% of work is done by the computer.
A computer is often referred to as a data processor because it can store,process and retrieve data whenever desired.The activity of processing data using a computer is called data processing. Data processing consists of three sub activites:-capturing input data, manipulating the data, and managing output results.Hence,data is raw material used as input to data processing and information is processed data obtained as output of data processing.


  1. Computer is a very powerful and useful tool.The power and usefulness of this tool are maily due to its following characteristics:
  2. Automatic,
  3. Speed,
  4. Accuracy,
  5. Diligence[the quality of doing work carefully and thoroughly],
  6. Versatility[ability to be adapted to many different functions or activities],
  7. Power of remembering,
  8. No I.Q.[It cann't take it's own decisions,and has to be instructed what to do and in what sequence]
  9. No feelings.


"Generation" in computer provides a framework for the growth of computer industry based on key technologies developed.There are totally five computer generations known until today.


The early computers were manufactured using vacuum tubes as electronic switching device.A vacuum tube was a fragile glass device using filaments as a source of electronics and could control and amplify electronic signals.It was the only high-speed electronic switching device available in those days.These vacuum tube computers could perform computations in miliseconds and were known as first-generation computers.

First-generation computers worked on the principle of storing program instructions along with data memory of computer so that they could automatically execute a program without human intervention.Memory  of these computers used electromagnetic relays and users fed all data and instructions into the system using punched cards.Programmers wrote instructions  in machine and assembly languages because of lack of high-level programming languages in those days.Ex:-ENIAC(Eletronic Numerical Integrator and Calculator).


  1. Fastest calculating device,
  2. Very big in size,
  3. Very high power consumption,
  4. Prone to frequent hardware failures,
  5. Required constant maintenance,
  6. Difficult to program and use;so they had limited commercial use,
  7. Commercial production is difficult and costly.
  8. Not transportable.

Second Generation(1955-1964)

John Bardeen,Willian Shockley and Walter Brattain invented a new eletronic switching device called transistor at Bell Laboratories in 1947.


  1. More rugged and easier to handle,
  2. Made up of germanium semiconductor material,
  3. Switching circuits made of transistors could operate much faster,
  4. Smaller than tube,
  5. less expensive,

Memory of second generation computers was composed of magnetic cores.Magnetic disk and magnetic tape were the main secondary storage media used.FORTRAN,COBOL,ALGOL and SNOBOL are the high level programming languages used.


  1. More faster,
  2. Smaller in size,
  3. Consumed less power,
  4. Faster and larger primary and secondary storage.

Third Generation(1964-1975)

In 1958,Jack St.Clair Kilby and Robert Noyce invented the first integrated circuit.Integrated circuits(called ICs) are circuits consisting of several electronic components like transistors,resistors and capacitors grown on a single chip of silicon eliminating wired interconnection between components.IC technology was also known as "microelectronics" technology.Initially the integrated circuits contained only about ten to twenty components.This technology was named small-scale integration(SSI).Later integrate up to about hundred components on a single chip.This technology was known as medium scale integration(MSI).
Third generation computers were manufactured using IC. ICs were smaller,less expensive to produce, more rugged and reliable,faster in operation,dissipated less heat, and consumed less power than circuits built by wiring electronic components manually.Hence they were more powerful,more reliable,less expensive,smaller,and cooler to operate.It used larger capacity magnetic disks and tapes.FORTRAN and COBOL high level programming languages were used. Third Generation used Timesharing operating system. Ex:-IBM 360
  1. More powerful{1 million instructions per second}, 
  2. smaller,
  3. consumed less power,
  4. more faster,
  5. easier to use and cheaper.

Fourth Generation(1975-1989) 

A verage number of electronic components packed on a silicon chip doubled each year after 1965.This progress soon let to the era of large-scale integration(VLSI),when it was possible to integrate about one million electronic components on a single chip.This progress led to a dramatic development-creation of a microprocessor.It started a new social revolution-personal computer(PC) revolution.
High-speed computer networking also developed during fourth-generation  like local are networks (LANS) became popular for connecting computers within an organization or with in a campus and similarly wide area networks(WANS) became popular for connecting computers located at larger distances.
Ex:-IBM PC and its clones,TRS-80.


  1. PCs were smaller and cheaper, 
  2. No air conditioning was required for PCs.
  3. consumed less power,
  4. more reliable and less prone to hardware failures,
  5. faster and larger primary and secondary storage,
  6. general purpose machines.

Fifth Generation(1989-Present)

The fifth generation computer system was an initiative Japan's Ministry of International trade and Industry(MITI),begun in 1982,to create computers using massively parallel computing and logic programming.VLSI technology became ULSI(Ultra-Large-Scale Integration) technology in fifth generation resulting in production of microprocessor chips having ten million electronic components.Fifth-generation powerful supercomputers based on parallel processing technology.They used multiple processors and were of two types-shared memory and distributed memory parallel computers.    
Multithreading technology is a popular way to improve application performance through parallelism.Multicore operating system can run multiple programs at the same time on a multicore chip with each core handling a separate program.In fifth generation JAVA programming language and parallel programming libraries like MPI(message passing interface) and PVM(parallel virtual machine) are used.MPI is used for distributed memory parallel computers and PVM is used for shared memory parallel computers.Ex:-IBM notebooks,PARAM supercomputers.
  1. more powerful,
  2. portable PCs,
  3. smaller in size,
  4. consume less power,
  5. very powerful mainframes,
  6. general-purpose machines.
Author/Written by: Mr Hemant Singh (Founder)
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