Evolution of Digital Computers

First mechanical machine capable of automatically performing arithmetic operations appeared in 1623, but it was not popular. In 1642 Blaise Pascal made a mechanical adding machine. It performed addition and subtraction automatically. In 1671 Gottfried Leibriz made a machine which was able to perform multiplication and division automatically. These machines performed computation in single step. In 1823, Charles Babbage made a multi-step mechanical computer. The successful general purpose mechanical digital computers were built in 1930s. in these machines electromechanical relay were used. Binary digits instead of decimal digits were used to represent numbers. 

  First Generation Computers (1946-1954)

The first electronic computer ENIAC was built in 1946. it used electronic valves as its main components. An improved design of electronic computer was given by Von Neumann. The digital computer using electronic valves are known as first generation computers (1946-1954). Example of first generation computers are: ADVAC, IBM 701, IBM 704, UNIVAC I etc. first generation computers used assembly language as programming language. 

 The Second Generation Computers (1955-1964)

The second generation computers used transistor instead of vacuum tubes as CPU components and ferrite core for main memory. Example of second generation computers are : IBM 1620, IBM 7090, CDC 1604, PDP 5 etc. second generation computers used high level language like FORTON, ALGOL, COBOL etc. 

 Third Generation Computers (1965-1971)

 

Third generation computers used IC’s instead of transistors. ICs were also used for main memory. Multiprogramming, multiprocessing, pipelining techniques were used in these computers. Microprogramming was developed to simplify the design of the computers. Examples of third generation computers are: IBM 370, CDC 7600, STAR 100 etc. 

 Fourth Generation Computers (1971-1980)

 

Microprocessors appeared in 1970s. Computers employing microprocessors are fourth generation computers. Computers available today are fourth generation computers. PCs, mini, mainframe and super computers all are 4th generation computers. Some examples are: CRAY Y –MPC(1992), IBM ES (9000), IBM PS/2 model 80, WIPRO LANDMARK 860, HCL Magnum 040 series (68040 CPU), HP 9000 (series 800) etc.

Fifth Generation Computers (1980 onward)

Fifth generation computers are in research and development stage. U.S.A. and Japan have projects to develop fifth generation computers. These computers will use ULSI chips which contains millions of components on a single chip. These computers will employ intelligent programming, knowledge based problem solving technique, highly integrated very powerful microprocessors and highly improved man machine interface. Computers will work in natural language like English. Computers will accept speech as input signal. They will have vision and hence they will be able to see surrounding.