Sunday, 13 March 2016

Five Generations of Computers

The development of electronic computers can be divided into five generations depending upon the technologies used. The following are the five generations of computers.

First Generation of Computers (1942-1955)

UNIVAC 1 First Generation Computer
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The beginning of commercial computer age is fromUNIVAC (Universal Automatic Computer). It was developed by two scientists Mauchly and Echert at the Census Department of United States in 1947.The first generation computers were used during 1942-1955. They were based on vacuum tubes. Examples of first generation computers are ENIVACand UNIVAC-1.


  • Vacuum tubes were the only electronic component available during those days.
  • Vacuum tube technology made possible to make electronic digital computers.
  • These computers could calculate data in millisecond.


  • The computers were very large in size.
  • They consumed a large amount of energy.
  • They heated very soon due to thousands of vacuum tubes.
  • They were not very reliable.
  • Air conditioning was required.
  • Constant maintenance was required.
  • Non-portable.
  • Costly commercial production.
  • Limited commercial use.
  • Very slow speed.
  • Limited programming capabilities.
  • Used machine language only.
  • Used magnetic drums which provide very less data storage.
  • Used punch cards for input.
  • Not versatile and very faulty.

Second Generation Computers (1955-1964)

IBM 1400 Series Second Generation Computers
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The second generation computers used transistors. The scientists at Bell laboratories developed transistor in 1947. These scientists include John Barden, William Brattain and William Shockley. The size of the computers was decreased by replacing vacuum tubes with transistors. The examples of second generation computers are IBM 7094 seriesIBM 1400 series and CDC 164 etc.


  • Smaller in size as compared to the first generation computers.
  • The 2nd generation Computers were more reliable
  • Used less energy and were not heated.
  • Wider commercial use
  • Better portability as compared to the first generation computers.
  • Better speed and could calculate data in microseconds
  • Used faster peripherals like tape drives, magnetic disks, printer etc.
  • Used Assembly language instead of Machine language.
  • Accuracy improved.


  • Cooling system was required
  • Constant maintenance was required
  • Commercial production was difficult
  • Only used for specific purposes
  • Costly and not versatile
  • Puch cards were used for input.

Third Generation Computers (1964-1975)

IBM 360 Third Generation Computers
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The Third generation computers used the integrated circuits (IC). Jack Kilby developed the concept of integrated circuit in 1958. It was an important invention in the computer field. The first IC was invented and used in 1961. The size of an IC is about ¼ square inch. A single IC chip may contain thousands of transistors. The computer became smaller in size, faster, more reliable and less expensive. The examples of third generation computers are IBM 370, IBM System/360,UNIVAC 1108 and UNIVAC AC 9000 etc.


  • Smaller in size as compared to previous generations.
  • More reliable.
  • Used less energy
  • Produced less heat as compared to the previous two generations of computers.
  • Better speed and could calculate data in nanoseconds.
  • Used fan for heat discharge to prevent damage.
  • Maintenance cost was low because hardware failure is reare.
  • Totally general purpose
  • Could be used for high-level languages.
  • Good storage
  • Versatile to an extent
  • Less expensive
  • Better accuracy
  • Commercial production increased.
  • Used mouse and keyboard for input.


  • Air conditioning was required.
  • Highly sophisticated technology required for the manufacturing of IC chips.

Fourth Generation Computers (1975-Present)

IBM PC fourth generation computers
The fourth generation computers started with the invention of Microprocessor. The Microprocessor contains thousands of ICs. Ted Hoff produced the first microprocessor in 1971 for Intel. It was known as Intel 4004. The technology of integrated circuits improved rapidly. The LSI (Large Scale Integration) circuit and VLSI (Very Large Scale Integration) circuit was designed. It greatly reduced the size of computer. The size of modern Microprocessors is usually one square inch. It can contain millions of electronic circuits. The examples of fourth generation computers are Apple Macintosh & IBM PC.


  • More powerful and reliable than previous generations.
  • Small in size
  • Fast processing power with less power consumption
  • Fan for heat discharging and thus to keep cold.
  • No air conditioning required.
  • Totally general purpose
  • Commercial production
  • Less need of repair.
  • Cheapest among all generations
  • All types of High level languages can be used in this type of computers


  • The latest technology is required for manufacturing of Microprocessors.

Fifth Generation Computers (Present & Beyond)

Scientists are working hard on the 5th generation computers with quite a few breakthroughs. It is based on the technique of Artificial Intelligence (AI). Computers can understand spoken words & imitate human reasoning. Can respond to its surroundings using different types of sensors. Scientists are constantly working to increase the processing power of computers. They are trying to create a computer with real IQ with the help of advanced programming and technologies. IBM Watson computer is one example that outsmarts Harvard University Students. The advancement in modern technologies will revolutionize the computer in future.

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