Compatible Time-Sharing System

The Compatible Time-Sharing System (CTSS) was the first general purpose <a href="/facts/Time-sharing/LE5XT9Go">time-sharing</a> <a href="/facts/Operating_system/8XTuvMh2">operating system</a>. Compatible Time Sharing referred to time sharing which was compatible with <a href="/facts/Batch_processing/hKY2rX3N">batch processing</a>; it could offer both time sharing and batch processing concurrently.
CTSS was developed at the <a href="/facts/MIT_Computation_Center/0tc1NpJ0">MIT Computation Center</a> ("Comp Center"). CTSS was first demonstrated on MIT's modified <a href="/facts/IBM_709/N8RAWUTP">IBM 709</a> in November 1961. The hardware was replaced with a modified <a href="/facts/IBM_7090/RpY2uI1k">IBM 7090</a> in 1962 and later a modified <a href="/facts/IBM_7094/RpY2uI1k">IBM 7094</a> called the "blue machine" to distinguish it from the Project MAC CTSS IBM 7094. Routine service to MIT Comp Center users began in the summer of 1963 and was operated there until 1968.
A second deployment of CTSS on a separate IBM 7094 that was received in October 1963 (the "red machine") was used early on in <a href="/facts/MIT_Computer_Science_and_Artificial_Intelligence_Laboratory/mTg66jb9">Project MAC</a> until 1969 when the red machine was moved to the Information Processing Center and operated until July 20, 1973. CTSS ran on only those two machines; however, there were remote CTSS users outside of MIT including ones in California, South America, the <a href="/facts/University_of_Edinburgh/L69HscH9">University of Edinburgh</a> and the <a href="/facts/University_of_Oxford/ExVVQL6V">University of Oxford</a>.

Compatible Time-Sharing System open-in-new

Compatible Time-Sharing System