The CIMS PL/I compiler

Abstract

CIMS PL/I is an implementation of PL/I on the Control Data 6600 computer. The most challenging aspect of implementing PL/I is dealing with the sheer size and complexity of the language; since a PL/I compiler is an inherently large object, building one is a good way to test the limits of ideas on compiler construction and programming methodology. Version 1 of CIMS PL/I has been in active use since 1973 and includes roughly 70% of the full language, but is limited by some severe design flaws. Version 2 is now under development; the parser and the declaration processor are in excellent working order, but the later passes are still being worked on. In this paper I shall describe Version 2 as though it already existed in full. Version 2 is intended to implement full ANSI Standard PL/I [1], and the passes that have been completed accept the full language. Both versions are themselves written almost entirely in PL/I, and have been developed using boot-strapping methods.