The
IBM 700/7000 series is a series of large-scale (
mainframe) computer systems that were made by
IBM through the 1950s and early 1960s. The series includes several different, incompatible processor architectures. The 700s use
vacuum tube logic and were made obsolete by the introduction of the
transistorized 7000s. The 7000s, in turn, were eventually replaced by
System/360, which was announced in 1964. However the 360/65, the first 360 powerful enough to replace 7000s, did not become available until November 1965. Early problems with
OS/360 and the high cost of converting software kept many 7000s in service for years afterward.