Dictionary meaning of generation is “all of the people born and living at about same time, regarded collectively”.

In computer science meaning of generation is “step in technology” or “change in technology” or “change in hardware and software” with respect to time.

Generation of computer distinguishes between different hardware and software changes in the field of computer science with respect to processing speed, size, storage and cost. The following are the different types of computer generation.

1. First Generation Computer (1942-1955)

  • First generation computers were the fastest calculating machine of their time.
  • Vacuum tubes, electromagnetic relay memory, punched card were used to perform any task.
  • Machine and Assembly language were used as software.
  • Computer of this generation were bulky in size and vacuum tube emitted large amount of heat and thus consumed more electricity.
  • Computers of this generation were very costly to use it commercially.
  • Example: ENIAC (Electronic Numerical Integrator and Calculator), EDVAC (Electronic Discrete Variable Automatic Computer), IBM 701

2. Second Generation Computer (1955-1964)

  • Second generation computer were more faster than first generation computer
  • Transistors were used instead of vacuum tubes and magnetic tape instead of electromagnetic relay to increase the overall efficiency of the system.
  • Batch operating system, high-level programming language, etc. were used as software.
  • Second generation computer were smaller, more reliable and faster than first generation computer.
  • Commercial production was still difficult and costly.
  • Example: Honeywell 400, UNIVAC (Universal Automatic Computer), IBM 7030.

3. Third Generation Computer (1964-1975)

  • Third generation computers were much more powerful than first and second generation computers. They were capable of performing about 1 million instructions per second.
  • IC’s (Integrated Circuit) were used with SSI (Small Scale Integration) and MSI (Medium Scale Integration) technologies instead of vacuum tubes and transistors.
  • Time-sharing operating system with high level programming language were used to increase the throughput of the system.
  • Computers of this generation were faster, smaller, more reliable and cheaper in comparison to first and second generation computers.
  • Example: IBM 360/370, PDP-8, PDP-II, CDC 6600, etc.

4. Fourth Generation Computer (1975-1989)

Fourth generation computers was an era of large scale integration (LSI) of electronic components over a single chip. A microprocessor contains all the circuits which were needed to perform arithmetic logic and control functions of the core activities of a computer.

  • IC’s with VLSI (Very Large Scale Integration) technology with microprocessors and large capacity hard disks were used for secondary storage.
  • Graphical User features with multiple windows and network based applications were used in this generation.
  • C programming language and UNIX features were introduced in this computer generation
  • Computers of this generation were small, affordable, reliable and more powerful with low maintenance and handling.
  • Easier to produce commercially.
  • Example: IBM PC, APPLE II, CRAY-I, CRAY-2,etc.

5. Fifth Generation Computer (1988- till present)

Fifth generation computers were much more smaller and handy that a user can compute anything while travelling. VLSI technology was replaced by ULSI (Ultra Large Scale Integration) through which ten million electronic components can be embedded on a single chip.

  • Computers of this generation were mostly powerful with larger main memory and secondary storage.
  • Computer of this generation were portable with internet facility.
  • Multimedia applications and internet based applications were the main key features of this generation computers.
  • Computers were more powerful, cheaper, reliable, fast, and can be produced commercially.
  • Computers of this generation can be used for artificial intelligence and can take logical decisions like human beings.
  • Example: IBM notebooks, Pentium PCs, PARAM 10000,etc.