Compatible Time-Sharing System

The Compatible Time-Sharing System, or the CTSS, was one of the first time-sharing operating systems; it was developed at MIT's Computation Center. CTSS was first demonstrated in 1961, and was operated at MIT until 1973. During part of this time, MIT's Project MAC had a second copy of CTSS, but the system did not spread beyond two sites (though this applies to many early computer systems). CTSS was described in a paper presented at the 1962 Spring Joint Computer Conference.