The historical development of computer can be studied from the age of its technology (Generation of Computer). Year of invention can also be considered while classifying computer. Thus
- 1st Generation Computer (1948-1958).
- 2nd Generation Computer (1959-1964).
- 3rd Generation Computer (1964-1971).
- 4th Generation Computer (1971-1982).
- 5th Generation Computer (1983-1988).
1st Generation Computers 1948 to 1958.
These computers are made up of vacuum tubes. It is a circuit consisting of wires and thermionic valves. Their characteristics include large size, generate heat, low capacity internal storage, uses magnetic drum and delay lines for storage and low speed. E.g. Electronic Discrete Variable Automatic Computer (EDSAC), Universal Automatic Computer (UNIVAC), etc.
2nd Generation Computers 1959-1964.
Are made up of diodes and transistors. Characteristics of this machine include small and faster than first generation computers, generate low heat, high capacity internal storage and uses magnetic core. The application used by these computers includes payroll and inventory, e.g. International Business Machines, Inc. (IBM 7030), NCR 315, Honeywell 800, etc.
3rd Generation Computers 1964-1971.
Are made up of micro integrated circuits from Small Scale Integration (SSI) with 10 to 20 interconnected transistors and diodes. It was upgraded to medium and later to Larger Scale Integration (LSI) where thousands of diodes and transistors were used on one chip. It uses complementary metal oxide semiconductor (CMOS) for storage instead of magnetic drum and magnetic core. Applications used include credit card billion, market forecast and airline reservation systems, e.g IBM S/360, 370 series, CDC 600, CDC 7600, PDP11, etc.
4th Generation Computers 1971-1982.
Uses Very Large Scale Integration Circuit ( VLSI), which lead to the production of microprocessors. It has extremely large and internal storage capacity. This marked the beginning of microcomputers, database systems, word-pressing packages, spreadsheet, graphics and games packages. It comes with remote communication facilities, multiprogramming facilities, uses high level language such as COBOL, etc.
5th Generation Computers 1983-1988.
Computers of this generation are characterised by Very Large Scale Integration Parallel Processing and Artificial Intelligence. It has speed and power over the previous generations. Applications include financial planning, management, database systems, desktop publishing, office automation, etc. Example of these computers include :NCR Tower 386, IBM PC/AT 286.