Multics, short for Multiplexed Information and Computing Service, was a mainframe time-sharing operating system. The Multicians history records that the project was “begun in 1965 and used until 2000,” making it one of the longest-lived operating systems ever built. It was a joint effort of MIT’s Project MAC, Bell Telephone Laboratories, and the General Electric Company, later continued by Honeywell.
The goal was deliberately grand. The 1965 Fall Joint Computer Conference paper that introduced Multics described the aim as creating “a computing system which is capable of meeting almost all of the present and near-future requirements of a large computer utility.” The designers imagined computing delivered like electricity or water, with many users drawing on a shared machine through their own terminals.
Multics pioneered ideas that are now standard, including a hierarchical file system, dynamic linking, segmented virtual memory, and a serious focus on security. The same 1965 paper highlighted the value of “the availability at one’s fingertips of facilities for editing, compiling, debugging, and running in one continuous interactive session.”
Bell Labs eventually withdrew from the project because Multics had grown large and slow. Two Bell Labs researchers who had worked on it, Ken Thompson and Dennis Ritchie, took the lessons and built a smaller, simpler system. They named it Unix as a wordplay on Multics, signaling something that did one job well rather than everything at once.