Transistor was first used in ___.

Transistors were first used in 2nd generation computers (roughly 1959-1964). 1st generation used vacuum tubes (1946-1959). 3rd generation used integrated circuits (1964-1971), and 4th generation used microprocessors (1971-present). The transistor revolutionized computing by replacing bulky, unreliable vacuum tubes with smaller, more reliable solid-state components.