CTSS

CTSS, which stood for the Compatible Time-Sharing System, was one of the first time-sharing operating systems; it was developed at Project MAC at MIT. CTSS was first published, as well as operated in a time-sharing environment, in 1961; in addition, it was the system with the first computerized text formatting utility, and one of the very first to have inter-user electronic mail.

Although CTSS was not an influential operating system in its technical detail, it was very influential in showing that time-sharing was viable, in the new applications for computers which were first instantiated there, and because of its successor, Multics, which all modern operating systems are intellectually descended from.

In addition to e-mail and text processing, Louis Pouzin created a facility called RUNCOM for CTSS. This took a collection of commands contained in a file and executed them; this is the direct ancestor of the Unix shell script. It also allowed parameter substitution.

CTSS was developed on the IBM 7094 mainframe computer.

Multics, which was also developed by Project MAC, was started in the 1960s as a successor to CTSS, for future use in multiple-access computing. Multics, infamously, was the operating system that led to the development of Unix in 1970.

ITS, the Incompatible Timesharing System, another early, revolutionary, and influential MIT time-sharing system, was produced by people who disagreed with the direction taken by Multics; the name was a hack on CTSS, as the name of Unix was later a hack on Multics

Table of contents

1 Alternative Meanings 2 See also 3 Further Reading 4 External Links

Alternative Meanings

CTSS also stands for Cray Time Sharing System, a separate system developed for Cray computers.

See also

• Fernando J. Corbató, project leader

Further Reading

• F. J. Corbató, M. M. Daggett, R. C. Daley, An Experimental Time-Sharing System (IFIPS 1962)
• Robert M. Fano, The MAC System: A Progress Report (MIT Project MAC, 1964) describes the usage of CTSS
• Jerome H. Saltzer, CTSS Technical Notes (MIT Project MAC, 1965) describes the internals of CTSS in some detail
• Jerome H. Saltzer, Manuscript Typing and Editing (MIT Computation Center, 1964) describes the world's first computerized text formatting system

External Links

• John McCarthy, Reminiscences on the History of Time Sharing presents the origin of the concept of time-sharing
• The IBM 7094 and CTSS a fascinating personal memoir of a system programmer on CTSS
• The Origin of the Shell describes the evolution of RUNCOM into the modern shell