History of Computers

Man always searched for a fast calculating device, it took a long time to invent a digital computer. A brief history behind the invention of computers is as follows:

1. Abacus :

It was the first computing device, and was developed in 600 B.C. It was used to perform simple addition and subtraction.

2. John Napier :

It was a cardboard multiplication calculator. It was designed in early 17th century.

3. Blaise Pascal :

It was invented in 1642, it could only add and subtract the numbers, division and multiplication was done by repeated addition and subtraction.

4. Leibnitz:

It was a the first calculator that could multiply and divide also, was invented in 1694.

5. Charles Xavier:

It could perform addition, subtraction and multiplication as well.

6. Charles Babbage:

In 1842, he developed an Analytical Engine that was automatic, which could perform 60 additions per minute.

Generations of Computers

  1. First Generation Computers (1946-1957)
  2. Second Generation Computers (1958-1964)
  3. Third Generation Computers (1965-1971)
  4. Fourth Generation Computers (1972 – 1977)
  5. Fifth Generation Computers (1978 – To date)

1. First Generation Computers (1946-1957)

The First generation computers were based on Vacuum tube, which was  a glass tube that controlled and amplified the electronic signals.

Examples: ENIAC & UNIVAC

ENIAC (Electronic Numerical Integrator and Calculator) invented in 1946, was the first electronic computer.

UNIVAC (Universal Automatic Computer)was the first digital computer, was used in business and industries.


  • Vacuum Tubes were the only electronic component available in those days.
  • This technology made possible to make electronic digital computers.
  • These computers could calculate data in milliseconds.


  • These were very large.
  • Consumed a large amount of energy.
  • Heated very soon due to thousands of vacuum tubes.
  • Not reliable
  • Air conditioning was required.
  • Constant maintenance was required.
  • Non-portable.
  • Costly commercial production.
  • Limited commercial use.
  • Quite slow speed.
  • Limited programming capabilities.
  • Used machine language only.
  • Used magnetic drums which provide very less facility of data storage.
  • Very faulty.

2. Second Generation Computers (1958-1964)

This was the age of Transistors, which is a small device that transfers electronic signals across a resistor.

The concept of Minicomputers was introduced.

Examples : IBM 7094 series, IBM 1400 series and CDC 164 etc.


  • Smaller size as compared to the first generation computers
  • More reliable
  • More energy-efficient
  • Were not heated because of less energy
  • Wider commercial use
  • Better portability
  • Better speed, could calculate data in microseconds
  • Used faster peripherals like tape drives, magnetic disks, line printer etc.
  • Used Assembly language instead of machine language
  • Accuracy improved


  • Commercial production was difficult
  • Also only used for specific purposes
  • Costly
  • Not versatile
  • Punch cards were used for input. 

3. Third Generation Computers (1965-1971)

It was the age of Integrated Circuits (ICs), which combined three electronic components onto a small silicon disc.

Scientists later managed to fit even more components on a single chip called a Semiconductor. The Concept of mainframes was introduced.

Examples: IBM System/360, UNIVAC 1108 and IBM 370 etc.


  • Smaller in size as compared to previous generation.
  • More reliable.
  • Less energy used 
  • Produced less heat as compared to previous generation computers
  • More good speed, could calculate data in nanoseconds.
  • Used fan for heat discharge and to prevent from damaging
  • Maintenance cost was low because hardware failure was rare
  • 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, keyboard for input


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

4. Fourth Generation Computers (1972 – 1977)

The fourth generation started with the invention of microprocessors. Microprocessors is a small chip containing thousands of ICs on it.

It greatly reduced the size of the computer. The modern microprocessors are usually one inch and can contain millions of electronic circuits.


  • Very small in size 
  • Less power consumption
  • Less heat generated 
  • Large fan for heat discharging and thus to keep cold
  • No air conditioning is required
  • Best speed to read instructions (one billionth per second)
  • Reliable and powerful
  • Totally general purpose
  • Commercial production 
  • Less need for repairing
  • Cheapest among all generations 
  • All types of high-level languages can be used in this type of computer


  • Highly sophisticated technology required for manufacturing microprocessors

5. Fifth Generation Computers (1978 – To date)

It is based on Artificial intelligence (AI), computers can understand spoken words instructions and imitate human reasoning.

Scientists are working to increase the speed of computers. They are trying to create a computer with a real IQ with the help of advanced programming and technologies.

With the rapid pace of technology, the high rate of introduction of new products, and the importance of software and communications as well as hardware, the classification by generation becomes less clear and less meaningful.

It could be said that the commercial application of new developments resulted in a major change in the early 1970s and that the results of these changes are still being worked out.