Lisp 1.5 is an ancient dialect from around 1962. The first implementation appeared on IBM mainframes (IBM 704, 709, 7090, 7094), but other implementations appeared on other systems. Some source code survives on the internet, but it seems that no one can run Lisp 1.5 programs today.

The features of Lisp 1.5 include garbage collection (of cons cells), recursion, and runtime evaluation (by an ''eval'' function).

• [http://www.softwarepreservation.org/projects/LISP/lisp15_family/ LISP 1.5 family]
• [http://www.frobenius.com/univac.htm LISP 1.5 for the Univac 1100]
• [http://www.mentallandscape.com/Lisp.htm Lisp 1.5 interpreters (CDC 6600, DEC VAX 11/780)]
• [http://c2.com/cgi/wiki?LispOnePointFive LispOnePointFive]