Explain the generations of computer.

Author: Tanmay Chakrabarty

First Published On: Saturday, May 21, 2016 at 2:54 AM

Very small amount storage spaceComputer systems reached today’s modern age step by step, these steps are called generations. In each generation computers with new features and functions starts to get the market and the older computers slowly gets replaced. IBM company started categorize the development of computers into generations, though not everyone in the industry including users will be agree on the periods of each generation. However, based on the use of electronic devices, computers systems can be categorized into following generations so far.

Generation of Computer: 

1. First Generation (1951 - 1959):

Vacuum tubes were used to build computers of this generation. These computers were so large in size because of using thousands of diode, triode, transistors, capacitors etc. and also used to use lot of electricity. These computers of this generation used produce a lot of heat, so those were more expensive to support by setting up cooling systems. Maintenance of these huge sized computers were complex and expensive. Following are some of the characteristics of the computers of first generation. 

First Generation (1951 - 1959)


  1. Use of vacuum tubes to make circuits
  2. Use of magnetic drums
  3. Use of machine language and symbols in instructions
  4. Very small amount of storage space
  5. Use of punch cards as I/O devices
  6. Huge in size and poor in mobility
  7. Very slow and less reliable output
  8. Use of high electricity
  9. Generates too much heats
  10. Complex and expensive to maintain

Example: UNIVAC I, IBM 650, MARK II, MARK III etc.


2. Second Generation (1959 - 1971): 

In 1947 transistors were invented, which was used in second generation computers to reduce the heat and size problem of the computers from first generation along with following characteristics

Second Generation (1959 - 1971)


  1. Use of transistors
  2. Magnetic memory and magnetic storage disks
  3. High speed I/O devices
  4. Invention and use of high level languages such as Fortran and Cobol.  
  5. Reduced size
  6. Solution to heat generation
  7. Communication by using telephone line
  8. Improvement of speed and reliability

Example: Honeywell 200, IBM 1620, IBM 1400 etc.


3. Third generation (1965 - 1971):

Use of integrated circuits (IC) started the third generation of computer which reduced the size, price, use of electricity etc. IC also facilitates speed and reliability of computers. Development of IC enabled organizing the whole central processing unit in single chip. Use of monitor also started in this generation. Operating system was improved to a new level and high speed line printers were in use. Followings are some of the characteristics of third generation. 

Third generation (1965 - 1971)


  1. Use of Integrated Circuits (IC) instead of transistors
  2. Use of Semi-conductor memory
  3. Small size than previous generation computers
  4. Use of magnetic storage devices
  5. Improved faster operations and more dependable output
  6. Use of mini computers
  7. Use of monitors and line printers
  8. Use of high level programming languages
  9. Less expensive than 2nd generation computers
  10. Less expensive maintenance cost

Examples: IBM 360, IBM 370, PDP-11 etc.


4. Fourth generation (1971 - present):

The computers that we use now-a-days are the computers from fourth generation. From this generation more use of semi-conductors in memory started. Microprocessors has been created with LSI (Large Scale Integration) and VLSI (Very Large Scale Integration). The size and price of computers has both been reduced to significant levels. Followings are some of the characteristics of computers from fourth generation.
Fourth generation (1971 - present)


  1. Very Large Scale Integration
  2. Microprocessor and Microcomputers
  3. Extended memory
  4. Improvement of dependability 
  5. Use of program packages

Example: IBM 3033, Sharp PC – 1211 etc.


5 Fifth generation (future):

Computers from fourth generation are in use of everyday work. Japan and America is still trying to automate the system itself. Following are some of the characteristics of computers from fifth generations

Fifth generation (future)


  1. Multi-processor based system.
  2. Use of AI
  3. Use of optical fiber in circuits
  4. Development of the elements of programs
  5. Automated audio in any language to control the workflow of the computer
  6. Magnetic enabled chips 
  7. Huge development of storage
  8. More powerful micro and macro computers
  9. Development of enormous powers with AI



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