Essential Guide to Computing: The Story of Information Technology, The

Mainframe Systems

Even IBM's second generation of mainframes, the 1400 series, lacked a formal OS. It wasn't until the revolutionary System 360, introduced in 1964, that IBM provided a complete version of what we would today call an operating system, the OS/360. The new software was pretty limited in contemporary terms; it was still a batch processing OS. Time sharing didn't appear (in volume, at least) until IBM's System 370 entered the market in 1970. OS/360, which hit the magic million lines of code benchmark, was big and complex by comparison to almost any other piece of contemporary software. Its slow and tortured development was a harbinger of what came to be known in the 1970s as the "software crisis." For one thing, OS/360's developers ...