Programmable Command Language

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File Format
Name Programmable Command Language
Extension(s) .pcl
Released 1983

Programmable Command Language (PCL) was created at Carnegie Mellon University to enable the development of new commands to be invoked from the command line of DEC TOPS-20 mainframes, which were in heavy use in universities from the late 1970s through the 1980s. It is not connected with the printer command language PCL.

TOPS-20 had a very advanced command line interface with some user-friendly features such as context-sensitive help and suggested command completion while a command was being input from a terminal. PCL allowed developers to interface with this system to provide similar help and completion functions for the commands they were developing.

A set of structured programming constructs, described in the reference guide as "ALGOL-like", was provided, along with commands geared toward specific TOPS-20 features including access to its filesystem.

PCL programs were created as plain-text files, then compiled into TOPS-20 executables.


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