CTSS (Compatible Time-Sharing System) was developed in the early 1960s by the MIT Computation Center for the IBM 7090 and IBM 7094 mainframe computers. CTSS was the first general-purpose time-sharing operating system.

Choose host “ibm7094” from the SDF Vintage Systems menu.

When you have connected to CTSS, you will see a message similar to the following:

MIT8C0 2 USERS AT 06/30/72  814.6, MAX = 30
READY.

Log in with the command login guest. (Or use your personal log in ID instead of “guest”.)

After the red Password prompt, enter the password “guest” (or your own password).

Enter the command logout.

(If you are not returned to the SDF Vintage Systems menu, press the escape character (Ctrl-]), then at the lcmtelnet> prompt enter q.)

• F. Corbató, M. Daggett, R. Daley, R. Creasy, J. Hellwig, R. Orenstein, L. Korn, The Compatible Time-Sharing System – A Programmer's Guide. Cambridge, MA: The M.I.T. Press, 1963. https://bitsavers.org/pdf/mit/ctss/CTSS_ProgrammersGuide.pdf. [Accessed June 30, 2024].
• P. Crisman, editor, The Compatible Time-Sharing System – A Programmer's Guide 2nd ed. Cambridge, MA: The M.I.T. Press, 1969. https://bitsavers.org/pdf/mit/ctss/CTSS_ProgrammersGuide_Dec69.pdf. [Accessed June 30, 2024].
• E. Kliman, Abstracts of CTSS Console Commands. Massachusetts Institute of Technology: 1965. https://bitsavers.org/pdf/mit/ctss/CC-239-3_Abstracts_of_CTSS_Console_Commands_Mar65.pdf. [Accessed June 30, 2024].
• Bitsavers' Computing Archive, “CTSS”, https://bitsavers.org/pdf/mit/ctss/. [Accessed June 30, 2024].