Control Data Corporation Dead
The company Cray built the 6600 for — supercomputers and the PLATO education system. Broke itself into pieces in 1992; Ceridian is its survivor.
William Norris founded CDC in 1957 with Sperry Rand colleagues. Seymour Cray's 6600 (1964) — built in a secluded Wisconsin lab — was the fastest computer on Earth and coined 'supercomputer'; the 7600 followed.
The PLATO system (UIUC, 1960–2006) pioneered forums, message boards, online education, and multiplayer games decades early. Norris was a famously ethical CEO ('social responsibility'), but the 1980s were brutal; CDC dissolved itself into Ceridian in 1992.