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The Dartmouth Time-Sharing System, or DTSS for short, was the first large-scale time-sharing system to be implemented successfully. Its implementation began at Dartmouth College in 1963 by a student team under the direction of John Kemeny and Thomas Kurtz with the aim of providing easy access to computing facilities for all members of the college. By 1964 the system was in use where it remained so until the end of 1999. DTSS was originally implemented to run on a GE-200 series computer with a GE Datanet 30 as a terminal processor that also managed the 235. Later, DTSS was reimplemented on the GE 635, still using the Datanet 30 for terminal control. The 635 version provided interactive time-sharing to up to nearly 300 simultaneous users in the 1970s, a very large number at the time.

Because of the educational aims, ease of use was a priority in DTSS design.

DTSS implemented the world's first Integrated Design Environment: a command-based system implementing the following commands.

• NEW -- to name and begin writing a program
• OLD -- to retrieve a previously named program
• LIST -- to display the current program
• SAVE -- to save the current program
• RUN -- to execute the current program

These commands were often believed to be part of the Dartmouth BASIC language by users but in fact they were part of the time sharing system and were also used when preparing ALGOL or FORTRAN programs via the DTSS terminals.

Any line typed in by the user, and beginning with a line number, was added to the program, replacing any previously stored line with the same number; anything else was immediately compiled and executed. Lines which consisted solely of a line number weren't stored but did remove any previously stored line with the same number. This method of editing provided a simple and easy to use service that allowed large numbers of teletypes as the terminal units for the Dartmouth Timesharing system.

In the mid-1970s, the nascent network included some users at other schools and institutions around the East Coast (including Goddard College and the U.S. Merchant Marine Academy), connected with Model 33 teletypes and modems. The system allowed email-type messages to be passed between users and real-time chat via a precursor to the unix 'talk' program.

In 2000 a project to recreate the DTSS system on a simulator was undertaken and as a result DTSS is now available for Windows systems and for the Macintosh computer.

• DTSS reborn site
• DTSS user manual October 1964
• Scans of original documentation and software
• Kemeny's Kids discussion forum for original creators