The first generation of computers used vacuum tubes as the basic components for memory and circuitry for the CPU (Central Processing Unit) . These tubes, like electric bulbs, produced a lot of heat and the installations used to fuse frequently. Therefore, they were very expensive and only large organizations were able to afford them. The period of the first generation was from 1946-1959. The first generation of computers was characterized by the fact that operating instructions were made-to-order for the specific task for which the computer was to be used. Each computer had a different binary-coded program. The main features of the first generation are:

• Vacuum tube technology
• Unreliable
• Supported machine language

In this generation, mainly batch processing operating systems were used. Punch cards, paper tape, and magnetic tape were used as input and output devices. The first generation of computers was heavy and huge. They performed arithmetic calculations by exploiting vacuum tubes. Their programming was very difficult, and they consumed a lot of electricity.