History and Types of Computers

            
             The history of electronic computers is divided into five generations.
            
             We consider first generation of computer by 1946, when binary system was used and concept of pre-stored instructions as programs were introduced. This generation continued till 1959. In 1946 ENIAC (Electronic Numerical integrator And Calculator) was developed as a result of military need. It was too large to be kept as it took up all space in a 20x40 square feet room and used 19000 vacuum tubes, 70,000 resistors and 500,000 solder connections. It could perform 5,000 additions in a second. It is said that the lights of nearby areas was dimmed when ENIAC was turned on because of its high power consumption.
             In 1944 a British man John Von Newman developed EVAC (Electronic Discrete variable Automatic Computer). In 1951 UNIVAC (Universal Automatic Computer) was developed. In 1955 IBM emphasized business problems and developed a vacuum tube computer called IBM-650.
             The major invention of this period was vacuum tubes. In this generations Punch Card were used as data storage medium. These computers were operated by a language called machine language.
             In the end Assembly language was developed and reduced the work of programming.
             Application :-.
             These computers were used for record keeping and payroll processing.
             Advantages :-.
             1. Vacuum tubes were used as electronic component.
             2. These computers were the fastest computing device of their time.
             3. Computations were performed in milliseconds.
             Disadvantages :-.
             1. Large size.
             2. Low efficiency.
             3. Noise.
             4. Frequently hardware failure.
             5. Air conditioning was required.
             Second Generation :-.
             The period of this generation is from 1959 to 1964 during this period transistors were used as internal logic circuits of computers. These computers could execute 200,000 instructions per second. The size of main storage memory was increased. The Input/Output devices became much faster by the use of magnetic tape. Through this period, low level programming languages were used, however the high level languages like FORTRAN and COBOL were also developed ad used.