Generations of Computers
A computer is an electronic device that accepts data (input), processes it under the control of a stored program, and gives information (output). The word comes from compute, to calculate. The basic cycle is Input → Process → Output → Storage.
The five generations
| Generation | Period | Key technology | Examples and features |
|---|---|---|---|
| First | 1940 to 1956 | Vacuum tubes | ENIAC, EDVAC, UNIVAC. Huge, hot, slow, unreliable. Machine language. Used punched cards and magnetic drums. |
| Second | 1956 to 1963 | Transistors | Smaller, faster, cheaper. Assembly language and early high-level languages (FORTRAN, COBOL). Magnetic tape and disk. |
| Third | 1964 to 1971 | Integrated Circuits (IC) | Many transistors on one chip. Operating systems, keyboard and monitor, high-level languages (BASIC, Pascal). |
| Fourth | 1971 to present | Microprocessor (VLSI) | Whole CPU on one chip. Intel 4004 (1971) was the first microprocessor. Personal computers, GUI, networks, the Internet. |
| Fifth | Present and beyond | ULSI, AI, parallel processing | Artificial intelligence, robotics, natural-language processing, quantum computing. |
Pioneers and milestones
| Person or machine | Contribution |
|---|---|
| Abacus | Oldest calculating tool. |
| Blaise Pascal | Pascaline (1642), a mechanical adding machine. |
| Charles Babbage | Father of the Computer. Designed the Difference Engine (1822) and the Analytical Engine (1837), which had an input, store, mill (CPU) and output. |
| Ada Lovelace | First programmer, for her notes on the Analytical Engine. |
| Herman Hollerith | Punched-card tabulating machine for the US census (1890). His company became IBM. |
| Alan Turing | Turing machine, the theory of computation. Turing Test for machine intelligence. |
| John von Neumann | Stored program concept: data and instructions are kept in the same memory. |
| ENIAC (1946) | First general-purpose electronic digital computer. |
| Tim Berners-Lee | Invented the World Wide Web (1989 to 1991). |
Computers in India
- The first computer in India was the HEC-2M, installed at the Indian Statistical Institute, Calcutta in 1956. TIFRAC at TIFR Mumbai was the first indigenous machine.
- C-DAC (Centre for Development of Advanced Computing, Pune) built the PARAM series of supercomputers, starting with PARAM 8000 in 1991. Vijay Bhatkar led this effort.
Keep practising
Notes are only half the work. Test yourself with questions and discuss doubts with other aspirants.
Prepared for exam revision from standard computer textbooks, Microsoft documentation and official sources. Features differ between Excel and Word versions (2016, 2019, 2021, 365) so check which version your exam follows. Found a mistake? Tell us.