To install this package on CP/M, download the ZIP file and unpack it. It will create a folder with the same name as the package, containing the files shown.

Download PLM-ISIS-MPM2-HACK.zip containing all files below.

README.TXT
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PL/M TEST STUFF
Tom Jennings
09 May 2026

This bundle contains many non-CP/M files, so do not attempt to
IMPORT it directly, or completely. It is a snapshot containing
a rough collection of files and information on the PL/M compiler
and ISIS emulator, ISX.COM.

The story is messy and complex. Hector Peraza did some amazing
and key work, and documentation, pulling together files released
long ago and writing new code to run the PL/M compiler on unix/linux.

The short of it, I believe is correct but could be wrong, is
that DR wrote much of CP/M etc in PL/M, using the Intel PL/M
compiler. This compiler, written in some FORTRAN, runs only
under Intel's ISIS OS for the MDS-800. It seems fairly complex
and has multiple overlays. 

But at some point DR created a somewhat-kludgey ISIS emulator
sufficient to run PL/M compilation tools on a highly customized,
modified, CP/M. The hacks involved a non-standard BIOS, a "hole"
in memory at f800 to accommodate a faked-up MDS-800 ROM jumptable,
and a special BDOS that calculates exact file size. All of this
is described in some (adequate? who knows) detail in Hector's
files.

I believe fZ80's architecture would be easy to install this custom
BIOS requirements and the hacked BDOS. But who knows if all information
needed has been provided. I am not willing to find out the
hard way at this time.

There is also ISIS user documentation that is very hard to find.

Everything in this folder is a jumble; the results of a week's
worth of web search, downloads, and link-following, before things
disappear entirely. I may add to the pile later. My usual M.O.
is to gather, collate, delete cruft and duplicates, and write
Notes For The Future. We'll see how far I get here. I usually don't
expose W.I.P. like this.


CONTENTS
---------------------------------------------

This is some of the DRI PL/M stuff from
Digital-Research-MPM/MPM2-source/mpm2src/PLM_WORK folder
with a random set of plm source to play with.


PLM80, ASM80 etc appear to be ISIS executables.

There is much PL/M stuff on this page:
http://cpmarchives.classiccmp.org/cpm/mirrors/www.unix4fun.org/z80pack/index.html

ALSO IN THIS BUNDLE

PL/M and ISIS documentation in PD/F form. This folder
is a jumble, just a collection of downloads. 

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