PL/M

The PL/M programming language (an acronym of Programming Language for Microcomputers^[2][3]) is a high-level language conceived and developed by Gary Kildall^[2][3][4][1] in 1973^[2][3] for Hank Smith^[2][3] at Intel for its microprocessors.

The language incorporated ideas from PL/I, ALGOL^{[citation needed]} and XPL,^[2][3] and had an integrated macro processor. As a graduate of the University of Washington Kildall had used their Burroughs B5500 computer,^[5] and as such was aware of the potential of high-level languages such as ESPOL for systems programming.

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 was the original implementation language for those parts of the CP/M operating system which were not written in assembler. Many Intel and Zilog Z80-based embedded systems were programmed in PL/M during the 1970s and 1980s. For instance, the firmware of the Service Processor component of CISC AS/400 was written in PL/M.

The original PL/M compiler targeted the Intel 8008. An updated version (PL/M-80) generated code for the 8080 processor, which would also run on the newer Intel 8085 as well as on the Zilog Z80 family (as it is backward-compatible with the 8080). Later followed compilers for the Intel 8048 and Intel 8051-microcontroller family (PL/M-51) as well as for the 8086 (8088) (PL/M-86), 80186 (80188) and subsequent 8086-based processors, including the advanced 80286 and the 32-bit 80386. There were also PL/M compilers developed for later microcontrollers, such as the Intel 8061 and 8096 / MCS-96 architecture family (PL/M-96).^[6]

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, for instance PLMX, which ran on other operating environments such as Digital Research CP/M, 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 source-code translators exist.

 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;
        DO WHILE NOT MATCH AND (MAXM > J);
        LAST,J = J + 1; /* START SCAN AT J */
        K = PA ; /* ATTEMPT STRING MATCH AT K */
            DO WHILE 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;

• PL/M-80 Programming Manual (PDF). Intel Corporation. January 1980 [1976]. Doc # 98-268B. Archived (PDF) from the original on 2019-12-21. Retrieved 2020-01-29.
• MCS-8 Guide to PL/M Programming (PDF). Intel Corporation. September 1973. Archived (PDF) from the original on 2019-12-21. Retrieved 2020-02-02.
• PL/M 386 Programmer's Guide (PDF). RadiSys Corporation. December 1999. Archived (PDF) from the original on 2006-08-14. Retrieved 2020-01-29. (NB. Includes entire syntax of PL/M in BNF notation.)
• McCracken, Daniel D. (1978). A Guide to PL/M Programming for Microcomputer Applications. Pearson / Addison-Wesley.

This article is based on material taken from the Free On-line Dictionary of Computing prior to 1 November 2008 and incorporated under the "relicensing" terms of the GFDL, version 1.3 or later.