The language incorporated ideas from PL/I, ALGOL and XPL, and had an integrated macro processor. Unlike other contemporary languages such as Pascal, C or BASIC, PL/M had no standard input or output routines. It included features targeted at the low-level hardware specific to the target microprocessors, and as such, it could support direct access to any location in memory, I/O ports and the processor interrupt flags in a very efficient manner. PL/M was the first higher level programming language for microprocessor based computers and the original implementation language for the CP/M operating system. Also the firmware of the Service Processor component of CISC AS/400 was written in PL/M. PL/M compilers have been made for the following processors/controllers: 8008, 8080, 8085, 8051, 8052, 8096, 80196, 8086/8088, 80186/80188, 286, and 386. While some PL/M compilers were "native", meaning that they ran on systems using that same microprocessor, e.g. for the Intel ISIS operating system, there were also "cross compilers" which ran on other operating environments such as Microsoft's DOS, and Digital Equipment Corporation's VAX/VMS.
PL/M is no longer supported by Intel, but aftermarket tools like PL/M-to-C translators exist (for examples, see External links, below).
FIND:PROCEDURE(PA,PB)BYTE;DECLARE(PA,PB)BYTE;/* FIND THE STRING IN SCRATCH STARTING AT PA AND ENDING AT PB */DECLARE J ADDRESS,(K, MATCH)BYTE;
J = BACK ;
MATCH = FALSE;DOWHILE NOT MATCH AND (MAXM > J);LAST,J = J +1;/* START SCAN AT J */
K = PA ;/* ATTEMPT STRING MATCH AT K */DOWHILE SCRATCH(K)= MEMORY(LAST) AND
NOT (MATCH := K = PB);/* MATCHED ONE MORE CHARACTER */
K = K +1;LAST=LAST+1;END;END;IF MATCH THEN/* MOVE STORAGE */DO;LAST=LAST-1;CALL MOVER;END;RETURN MATCH;END FIND;