Generation of Computers – Hardware Evolution of Computers

GENERATIONS OF COMPUTER: The term computer generation is often used in relation to the hardware of computers. Each phase of computer development is known as generation of computer.



The first generation computers were large in size. The technology was based on vacuum tubes and therefore a considerable amount of heat was produced. Such computers required large space and consumed huge amount of electrical power.

The language used for storing and processing data was machine language. These computers used magnetic tapes as output devices

Some of First Generation Computers are

  • ENIAC (Electronic Numerical Integrator and calculator)
  • EDVAC (Electronic Discrete Variable Automatic Computer)
  • UNIVAC I (Universal Automatic Computer)

Main Features

  • Vacuum tube technology
  • Magnetic core memories
  • Fastest computing devices of that time
  • Main application areas were scientific computation, payroll processing, record keeping etc.


  • Bulky in six and occupied a lot of space.
  • Unreliable and prone to frequent hardware failures.
  • Consumed too much of power.
  • Generated large amount of heat because of vacuum tubes.
  • Non portable.
  • Air conditioning required.



This generations of computers used solid state semiconductor devices. In 1959 the vacuum tubes were replaced by transistors. Therefore, physical size of the computer were greatly reduced.

Transistors were more durable than vaccum tubes. Fortran and Cobol were the high level language used on these computers. Magnetic cores were introduced as a primary memory.

These computers were comparatively smaller, faster and more reliable. IBM 1401 was a very popular second generation computers. IBM 1620 was most useful for scientific and Engineering applications.

Main Features

  • Transistor based
  • Smaller in size as compared to first generation computer.
  • More reliable and less prone to hardware failure.
  • Magnetic core memories as primary storage.
  • Magnetic disks were used as secondary storage.
  • Wider commercial
  • Computation time is microseconds.


  • Frequent maintenance needed.
  • They needed air conditioning.
  • Commercial production was still difficult. e.g., 1BM700, 1401, 1620, ATLAS etc.


Check out these Computers:



A big revolution took place in computers when transistors were replaced with ‘Integrated Circuits’ known popularly as chips. An IC is a silicon chip or wafer that contains all elements of an electronic circuit on a very small area in the form of microelectronic circuits.

The concepts of time sharing and multiprogramming also came into picture with this generation of computers. The size of the main memory also reached 4 megabytes.

The CPU’s became much more powerful with the capacity of carrying out 1 million instructions per second (MIPS).

Main Features:

  • Integrated circuit based technology.
  • Time sharing and multi-programming concepts were introduced.
  • Lower heat generation as compared to previous generations.
  • More reliable and cheaper.
  • Low power consumption.
  • Computational time reduced from micro to nano seconds because of shortened path cergth.

Draw Backs:

  • Complex and sophisticated technology required for manufacturing the CPU and other components. e.g., IBM 360/370, Burrough : B6500, etc.



The advent of the microprocessor chip marked the beginning of the fourth generation of computers. By early 1970’s large scale integration (LSI) of electronic circuit became possible with the packing of about 50000 transistors in a chip.

Integration of a complete CPU on a single chip was achieved at Intel corporation. This CPU on a single chip was termed us a microprocessor.

The emergent of the microprocessor led to the emergence of extremely powerful personal computers. The faster accessing and processing speeds and increased memory capacity helped in development of much more powerful operating systems.

New concepts such as microprogrammed, database management system, virtual memory etc. were developed.


  • LSI technology.
  • Development of microprocessor based technology.
  • Very small in size.
  • Much faster in computation as compared to previous generation
  • Negligible heat generation.
  • Production cost very less.


  • Complex and sophisticated technology required for manufacturing the CPU and other components. e.g., HCL workhorse, Magnum, Ille, etc.



The fifth generation computers using magnetic bubble memories and other recent developments are on the way. These computers are supposed to have thinking power i.e., they will have artificial intelligence.

These computers will be based on advances in silicon technology. In contrast to present DIPS/LIPS/Data/Logic Information Processing System, the fifth generation computers will have KIPS (Knowledge Information Processing System).

These VVLSI (Very Very Large Scale Integration) technology computers with sophisticated operating system interface capability are still in the development stage in the research laboratories of America and Japan.


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