Compatible Timesharing System

operating system (CTSS) One of the earliest (1963)

experiments in the design of interactive time-sharing

operating systems. CTSS was ancestral to Multics, Unix,

and ITS. It was developed at the MIT Computation Center

by a team led by Fernando J. Corbato. CTSS ran on a modified

IBM 7094 with a second 32K-word bank of memory, using two

2301 drums for swapping. Remote access was provided to up

to 30 users via an IBM 7750 communications controller

connected to dial-up modems.

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.

(1997-01-29)