The introduction of microprocessors brought pinball into the realm of electronic gaming. The electromechanical relays and scoring reels that drove games in the 1950s and 1960s were replaced in the 1970s with circuit boards and digital displays. The first pinball machine using a microprocessor was Flicker, a prototype made by Bally in 1974. Bally soon followed that up with a solid state version of Bow and Arrow in the same year with a microprocessor board that would be used in eight other machines until 1978 which included Eight Ball, the machine that held the sales record from 1977 to 1993. The first solid-state pinball is believed by some to be Mirco Games' The Spirit of '76 (1976), though the first mainstream solid-state game was Williams' Hot Tip (1977). This new technology led to a boom for Williams and Bally, who attracted more players with games featuring more complex rules, digital sound effects, and speech. Pinball would continue to rule the arcades until the video game boom of the '80s muscled them out, relegating them to life as retro gaming devices, though many still find them popular today.