Aircraft automation was invented to complement and assist human operators in carrying out tasks that were difficult or even impossible without machine assistance. Until the late 1960s, automation was largely devoted to maintaining aircraft control, leaving navigation, communications, and management functions to the flight crew. The 1970s saw the onset of a technological revolution as the expanding utility of digital computers stimulated the development of miniaturized microprocessors with new solid-state circuitry based on the transistor. The introduction of jet aircraft into civil aviation marked the beginning of a technological revolution. Long-range civil aircraft during the late 1930s, and military transport and bomber aircraft throughout World War II, were similarly equipped. The introduction of fly-by-wire systems in the A320/330/340 and B-777 has provided control system engineers with more flexibility to tailor aircraft control responses to match desired characteristics through software in the flight control computers. Reciprocating-engine aircraft had only limited inner-loop automation of power control systems.