First Generation = First Generation. The period of first generation was from 1942-1956. The computers of first generation used vacuum tubes as the basic components for memory and circuitry for CPU (Central Processing Unit). These tubes, like electric bulbs, produced a lot of heat and the installations used to fuse frequently. Second Generations = A transistor computer, now often called a second generation computer, is a computer which uses discrete transistors instead of vacuum tubes. ... A seco