"PLMX: a PL/M to Fit All Micros"
published in Infoworld Jan 21 1980. 
Presumably it's based on a press release from
thePLMX publisher - Herb Johnson Aug 2021

PLMX, billed as a universal high-
level language fur microprocessors, has
been introduced by Systems Con-
sultants, Inc. (SCI), of San Diego,
California. PLMX can be used with all
8- or 16-bit microprocessors known today. 
and its modular structure will
enable it to generate code for any such
microprocessor yet to be developed,
the company says. PLMX is designed
primarily for use in microcomputer
product development systems and in
real-time process control applications.

According to Dr. Jack Ingber,
manager of product development for
SCI, PLMX takes PL/M to its logical
conclusion. PL/M, originally derived
from PLII. is used only on 8080- and
8D86~based systems. Other versions,
such as PLIZ for the Z-30 and PL/65
for the 6500, are used only with those
speci?c microprocessors.

PLMX syntax is identical to that of
PL/M, which means that the entire
library of existing PL/M programs can
be compiled under PLMX. It also
means that through the PLMX com-
piler PL/M programs may be used on
microprocessors other than the 8080.

PLMX is said to be usable on any
8-or 16-bit microprocessor, but it can,
according to SCI, also be adapted to
interface with practically any operating
system. Currently, the PLMX compiler
can run under Tekdos and CP/M
operating systems. Tekdos is the
operating system for Tektronix‘s 8002A
Universal Microprocessor Develop-
ment System, and CP/M is an
operating system that can support just
about any 8080-based system in use to-
day, including many hobbyist and
small industrial systems. Interfaces to
other operating systems will be
available in 1980.

In addition, PLMX is a true compiler,
not an interpretive campiler such
as Basic or Pascal in some of their cur-
rent implementations. Since an inter-
preter musl be resident in ROM for ex-
ecution of programs, an interpretive
compiler requires a considerable
amount of merrlory space, thus restrict-
ing its usefulness in developing ROM-
based products.

As seen in the illustration, the struc-
ture of PLMX allows for one interface
to the operating system and another to
the particular microprocessor, neither
of which requires any modi?cation to
the main body of PLMX itself (i.e., to
the compiler). The interfaces to the dif-
ferent operating systems or to different
microprocessors are modularized and
therefore easily interchangeable. This
means that direct substitution of alter-
nate input/output routines or alternate
code generators is readily accomplished.

Included in the PLMX package are
run time routines and high level ex-
ecutive procedures that allow for a sim-
ple interface to the operating system.
These routines and procedures give the
user access to all system peripherals
and disk ?les.

PLMX source code compiles first to
an intermediate code that is
transparent to the user. This in-
termediate code is then converted by
the modular code generator into
assembly language code for the par-
ticular microprocessor. Code
generators for the 8080-8085, Z-80,
and 6800 are available now, with code
generators for the TI 9900 and RCA
1802 to appear early in 1980, SCI says.
Z8000, 6800 and 8086 code generators
will follow later in 1980.

Full access to the many functions of
the particuiar microprocessor is pro-
vided by PLMX. Based variable and
pointers allow for manipulation of
memory, including bit-by-bit
manipulation, which is especially im-
portant in process control.

PLMX, like PL/M, is a modular,
block-structured language. Large pro-
gramming projects can be broken
down into smaller modules, with each
module programmed, debugged, and
tested independently. Modules can
then be linked together. The maximum
module size, which is roughly propor-
titlnal to the number of source code
lines, is limited by the amount of pro-
gram memory available to the com-
piler. A system with 64K of program
memory can compile modules in excess
of 500 lines of source code.

The PLMX compiler, priced at
$1000, is housed on an eight-inch
diskette, but may also be placed on
hard disk. The user invokes the com-
pller to start the process; the final code
is space optimized, making the
language suitable for ROM-based pro-
grams. PLMX keeps the ROM and
RAM areas separate. In addition, the
programmer has access to the code at
any point after the compilation for
modi?cation, manipulation. etc. SCI
says.

Contact Systems Consultants, Inc.,
4015 Hancock St., San Diego, CA
921ll]; [714] 222-6381.