General Comprehensive Operating System

General Comprehensive Operating System (GCOS, /ˈdʒiːkoʊs/) is a family of operating systems oriented toward mainframe computers.

The original version of GCOS was developed by General Electric from 1962; originally called GECOS (the General Electric Comprehensive Operating Supervisor). The operating system is still used today in its most recent versions (GCOS 7 and GCOS 8) on servers and mainframes produced by Groupe Bull, primarily through emulation, to provide continuity with legacy mainframe environments. Note that GCOS 7 and GCOS 8 are separate branches of the operating system and continue to be developed alongside each other.