Once the strongest chess playing computer in the world. It searched approximately 2 million chess positions per second. Deep Thought became the first computer to defeat a grandmaster in tournament play by defeating Bent Larsen at the 1988 U.S. Open. Deep Thought tied for first place in the U.S. Open with Tony Miles. Deep Thought became the world computer champion in 1989 and defeated David Levy in a match later that year.
It was a precursor to Deep Blue, the computer that defeated Kasparov in the 1997 match. Kasparov accused IBM of cheating and demanded a rematch, but IBM refused and Deep Blue was retired shortly thereafter.