Interlisp-10, for Interactive Lisp, is an implementation of the Lisp programming language developed from 1966 at Bolt, Beranek and Newman (BBN) for TENEX, BBN's in-house PDP-10 operating system, and later DEC's TOPS-20 operating systems. From 1970, development of Interlisp was transferred to Xerox Palo Alto Research Center.

The language became popular with Stanford University AI researchers and at other principly US West-Coast institutions.

Interlisp was noted for its integration of interactive development tools into the the programming environment: debugger, Lisp-structure-aware editor, automatic correction tool, and analysis tools.

[More details on Interlisp features: * List structure oriented editor * Break package * File package * Record package * DWIM * CLISP * HelpSys * MasterScope (Which ones work on TWENEX?)]

Start Interlisp with the EXEC command @INTERLISP:LISP. Return to EXEC with the Interlisp command LOGOUT() or Ctrl-C.

For an example of basic Interlisp usage, see Interlisp Example Session on TWENEX.

• The Interlisp prompt character is a _.
• Interlisp is case-sensitive. Core functions are defined with uppercase names. DWIM can figure-out incorrect capitalization. (Note: Interlisp built-in function names should be typed in upper-case, although in many cases Interlisp can automatically correct names typed with incorrect case. Interlisp supports upper- and lower-case characters in user-defined names and in character string data.)
• EVALQUOTE command format
• Superbracket “]”
• TOPS-20 command line editing keys
• Interlisp is not identical to Lisp 1.5, but C. Weissman's Lisp 1.5 Primer is recommended as an introduction to the Lisp programming language for Interlisp users.

Warren Teitelman. Interlisp Reference Manual. (1978). Accessed: October 3, 2024. [Online]. Available: https://www.softwarepreservation.org/projects/LISP/interlisp/Interlisp-Oct_1978.pdf

Clark Weissman. Lisp 1.5 Primer. (1967). Accessed: October 3, 2024. [Online]. Available: http://www.softwarepreservation.org/projects/LISP/book/Weismann_LISP1.5_Primer_1967.pdf