PL/M (Programming Language for Microcomputers) is (as the name suggests) a language designed for microcomputer software, particularly system software.
It is approximately a very small subset of PL/1 (though not a strict subset).
The following statements from PL/1 (with some changes) were available:
- RETURN Additionally, a HALT statement, interrupt related statements and a number of compiler directive statements existed.
There are no built-in I/O statements - calls to appropriate routines would be made instead.
Unlike PL1, PL/M keywords are reserved and so cannot be used as identifiers. The Boolean operators are reserved words: AND, OR and NOT instead of the symbols: &, |, ¬.
Available datatypes (BYTE, WORD, etc.) reflected the available types of the microprocessors.
The declaration of structures in PL/M does not use level-numbers, instead a syntax more like C structs is used, e.g.:
DECLARE A STRUCTURE ( B BYTE, C WORD );
declares a structure A with two members, B and C.
PL/M was used in the development of the CP/M operating system and associated applications.
Compilers were available for a number of microprocessors including the 8080 Z80.
- [[wp:PL/M|Wikipedia page on PL/M]]: [https://en.wikipedia.org/wiki/PL/M]