A programming language created by Robin Popplestone in 1975, originally for the PDP-11. Pop-11 is stack-oriented, extensible, and efficient like FORTH. It is also functional, dynamically typed, interactive, with garbage collection like LISP, and the syntax is block structured like Pascal. AlphaPop is an implementation for the Macintosh from Computable Functions Inc. PopTalk and POPLOG from the University of Sussex are available for VAX/VMS and most workstations.