GENERATION OF COMPUTERS

HISTORY AND GENERATION OF COMPUTERS

First Generation (1946-1954)

The digital computers using electronic valves (vacuum tubes) are known as first-generation

computers. Some examples of the first-generation computers are International Business Machine’s IBM-700 series IBM-701, IMB-709, EDVAC (Electronic Discrete Variable Automatic Computer), and UNIVAC (Universal Automatic Computer). The first generation computers usually used Vacuum tubes as CPU components. The high cost of vacuum tubes prevented their use for main memory. Whirlwind I, constructed at MIT was the first computer to use ferrite core memory. The first generation computers

used assembly language for programming. They used fixed-point arithmetic.

Second Generation (1955-1964)

The second-generation computers used transistors used for CPU components, ferrite cores for main memory, and magnetic disks, drums and tapes for secondary memory. They used high level language such as FOTRON (1956) ALGOL (1960) and COBOL (1960) for programming. Floating-point arithmetic hardware was widely used. I/O processor was included to control input/output operations. Itrelieved CPU from many time-consuming routine tasks. Examples of second-generation computers are IBM 1620 (1960), IBM 7090 (1960), Control Data Corporation’s CDC 1604, Digital Data Corporation’s PDP1, PDP5 and PDP8 (PDP – Programmed Data Processor). PDP 8 was 12-bit minicomputer.

Third Generation (1965-1974)

The third-generation computers used IC’s (Integrated Circuits) for CPU components. In the

beginning, third generation computers used magnetic core memory. Later semiconductor memories

(RAMs and ROMs) were used. Semiconductor memories were LSI chips. Magnetic disks, drums, and tapes were used as secondary memories. Cache memory was also incorporated in the computers of third generation. Microprogramming, Parallel processing (pipelining, multiprocessor system, etc.), multi-

processing, multiprogramming, multi-user system (time-sharing system), etc. were just introduced. The

concept of virtual memory was also introduced. The examples of third generation computers are IBM370 series (1970) CDC 7600, PDP 11 (16bit minicomputer) etc.

Fourth Generation (1975 – up till now)

The fourth-generation computers use VLSI (Very Large Scale Integration) chips for both CPU and

memory. A CPU consists of one or more microprocessors. The latest microprocessors contain more than one million transistors. Semiconductors memory of 128 MB on a single chip is available. Cache memory is being provided on the CPU chip. Besides on-chip cache memory, external caches are also provided in the computer.Examples of fourth-generation computers are IBM PS/2 model 80, WIPRO LANDMARK 860, HP 9000 Model 870S/400 etc.

Fifth Generation

The fifth generation computers are still under development stage. Japan and USA have under

taken projects to design and develop such computers. These computers will use ULSI (Ultra Large Scale Integration) chips.

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