Related:

• Multics /muhl'tiks/ n. [from "MULTiplexed Information and Computing Service"] An early time-sharing operating system co-designed by a consortium including MIT
  GE, and Bell Laboratories as a successor to CTSS....
• GCOS:: /jee'kohs/ n. A {quick-and-dirty} {clone} of System/360 DOS that emerged from GE around 1970
  originally called GECOS (the General Electric Comprehensive Operating System)....
• GCOS /jee'kohs/ n. A quick-and-dirty clone of System/360 DOS that emerged from GE around 1970
  originally called GECOS (the General Electric Comprehensive Operating System)....
• Unix /yoo'niks/ n. [In the authors' words, "A weak pun on Multic
  very early on it was `UNICS'] (also `UNIX') An interactive time-sharing system invented in 1969 by Ken Thompson after Bell Labs left the Multics project, originally so he could play games on his scavenged PDP-7....
• UNIX:: /yoo'niks/ [In the authors' words, "A weak pun on Multics"] n.
  (also `Unix') An interactive time-sharing system invented in 1969 by Ken Thompson after Bell Labs left the Multics project, originally so he could play games on his scavenged PDP-7....
• CTSS: /C-T-S-S/ n. Compatible Time-Sharing System. An early (1963) experiment in the design of interactive time-sharing operating systems, ancestral to {{Multics}}, {{UNIX}}, and {{ITS}}.
  The name {{ITS}} (Incompatible Time-sharing System) was a hack on CTSS, meant both as a joke and to express some basic differences in philosophy about the way I/O services should be presented to user programs....
• econd-system effect: n. (sometimes, more euphoniously
  `second-system syndrome') When one is designing the successor to a relatively small, elegant, and successful system, there is a tendency to become grandiose in one's success and design an {elephantine} feature-laden monstrosity....
• multician: /muhl-ti'shn/ [coined at Honeywell, ca. 1970] n.
  Competent user of {{Multics}}. Perhaps oddly, no one has ever promoted the analogous `Unician'....
• mainframe: n. Term originally referring to the cabinet containing the central processor unit or `main frame' of a room-filling {Stone Age} batch machine.
  After the emergence of smaller `minicomputer' designs in the early 1970s, the traditional {big iron} machines were described as `mainframe computers' and eventually just as mainframes....