PL/M

PL/M

Appeared in	1972 (1972)
Developer	Gary Kildall at Digital Research
Influenced by	ALGOL, PL/I, XPL

The PL/M programming language (an acronym of Programming Language for Microcomputers) is a high-level language developed by Gary Kildall in 1972 for Intel for its microprocessors.

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 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: Intel 4004, 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).

PL/M Sample code:

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;

References

• Intel Corporation (1976). PL/M-80 Programming Manual. Doc # 98-268B.
• McCracken, Daniel D. (1978). A Guide to PL/M Programming for Microcomputer Applications. Pearson Addison-Wesley.

External links

• PL/M 386 Programmer’s Guide (PDF) – RadiSys Corporation, December 1999. Includes entire syntax of PL/M in BNF notation. Also available on Archive.org.
• Development Assistant for PL/M (DA-PL/M) – Commercial PL/M IDE from RistanCASE GmbH
• PLM2C - PL/M to C Translator – Commercial product from Alternative Solutions
• XTRAN Demonstration: Translating PL/M to C – Commercial product from Pennington Systems, Inc.

This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.