Compatible Timesharing System

Compatible Timesharing System

(operating system)(CTSS) One of the earliest (1963)experiments in the design of interactive time-sharingoperating systems. CTSS was ancestral to Multics, Unix,and ITS. It was developed at the MIT Computation Centerby a team led by Fernando J. Corbato. CTSS ran on a modifiedIBM 7094 with a second 32K-word bank of memory, using two2301 drums for swapping. Remote access was provided to upto 30 users via an IBM 7750 communications controllerconnected to dial-up modems.

The name ITS (Incompatible time-sharing System) was a hackon CTSS, meant both as a joke and to express some basicdifferences in philosophy about the way I/O services should bepresented to user programs.