The computer has evolved from a large-sized simple calculating machine to a smaller but much more powerful machine. The evolution of computer to the current state is defined in terms of the generations of computer. Each generation of computer is designed based on a new technological development, resulting in better, cheaper and smaller computers that are more powerful, faster and efficient than their predecessors. Currently, there are five generations of computer. In the following subsections, we will discuss the generations of computer in terms of

  • The technology used by them (hardware and software),
  • computing characteristics (speed, i.e.,number of instructions executed per second),
  • physical appearance, and
  • their applications.

First Generation (1940 to 1956): Using Vacuum Tubes

  • Hardware Technology The first generation of computers used vacuumimage tubes for circuitry and magnetic drums for memory. The input to the computer was through punched cards and paper tapes. The output was displayed as printouts.
  • Software Technology The instructions were written in machine language. Machine language uses 0s and 1s for coding of the instructions. The first generation computers could solve one problem at a time.
  • Computing Characteristics The computation time was in milliseconds.
  • Physical Appearance These computers were enormous in size and required a large room for installation.
  • Application They were used for scientific applications as they were the fastest computing device of their time.
  • Examples Universal Automatic Computer (UNIVAC), Electronic Numerical Integrator And Calculator (ENIAC), and Electronic Discrete Variable Automatic Computer (EDVAC).