Timeline of sample computer chess systems and their equivalent ratings over time
Computer History Museum
Chess-playing computers steadily improved their game throughout the 1970s and 1980s. By the late 1990s, microcomputers reached the same level of play as more expensive special-purpose computers. To obtain ratings, computers played against already-rated human opponents. Shown here are the estimated chess ratings of several top computer chess programs over time as well as the corresponding levels for human players.