Why do you want to know?

Unless it's for an existing project, or pure historical interest, I wouldn't have though it's worth it?

Note that PL/M was also available for 8080 and x86 families - so you might try asking on fora dedicated to those processors?

When searching, not that the oblique stroke ("slash") may or may not be present; ie "PL/M" or "PLM"

I found the following at http://foldoc.doc.ic.ac.uk/foldoc/fo...cgi?PL%2fM
Programming Language/Microcomputers. MAA (later Digital Research) for Intel, 1972. A very low level language incorporating ideas from PL/I, ALGOL and XPL. Integrated macro processor. Originally the implementation language for CP/M. "PL/M-80 Programming Manual", Doc 98-268B, Intel 1976. "A Guide to PL/M Programming for Microcomputer Applications", D. McCracken, A-W 1978. Versions: PL/M-80, PL/M-86, PL/M-286.