Generation of computers:

                 The generation of computers is basically differentiated by a fundamental hardware technology. Each new generation of computer is characterized by greater speed, large memory capacity and smaller size than the previous generation.

  Ø  First Generation:  The computer produced and used between 1940-1955 was called first generation. In this generation computer were characterized by vacuum tubes (valve) circuitry. Hence they were very large, they were placed in large air-conditioned rooms had small internal storage and were relatively very slow. The first generation machines used punched paper tape, punched card, magnetic wire, magnetic tape and printers as input/output devices. The trends, which were encountered during the era of first generation computers were:

-          The first generation computer control was centralized in a single CPU, and all the operations required a direct intervention of the CPU.

-          Punched cards were used as input device.

-          Magnetic tapes and magnetic drums were used as secondary memory.

-          Binary code or machine language was used as secondary memory

  Ø  Second Generation Computers:   The computer produced after 1955 are called second generation of computers. They had faster access and were more reliable than first generation of computers. In this generation Transistors replaced vacuum tubes of first generation period. By this time a wider range input/output devices such as higher performance magnetic tapes, magnetic drums and early magnetic disks were available. During the second generation, computer languages such as FORTRAN and ALGOL were introduced. The second generation of computers started with the advent of transistorized computers

  Ø  Third Generation Computers: IBM announced the third generation of computers in 1964 with its 360 line of computers. They were used integrated circuits(IC) in the hardware. It also had the provision of facilities for time- sharing and multi programming. The speed and storage capacity of their computers were much higher than the previous generation computers and the size was much reduced. This computers are low cost , size smaller , reduce in power and cooling requirements.

  Ø  Fourth Generation: The fourth generation computers were produced after 1970. The term fourth generation computer is used to designate micro computers which use large-scale integrated circuits (LSI) and very large integrated, had greater input/output capacity and system reliability. The most important criterion that can be used to separate them from third generation computers is that they have been designed work efficiently with the current generation of high level languages.

  Ø  Fifth Generation:  In October 1981, a conference of 300 computer scientists and engineers from fourteen countries was held in Japan to discuss the features of the fifth generation computers. This machine will incorporate artificial intelligence, which will not be far different from that of human intelligence. They will use stored reservoirs of knowledge to make expert judgment and decisions. They will process non-numerical information such as pictures and graphs.