CP/M Main Page

Last updated: 26 October 2009

• CP/M links
• CP/M information
• CP/M software
• ZINC - clones of some CP/M 3 utilities

If you are using an Amstrad PCW, you may be interested in my PCW page. If you've come here looking for PCW boot discs, you won't find them here; you need to go to LocoScript Software.

What is CP/M?

It's an operating system for 8-bit computers. It looks rather like DOS to use (only not so user-friendly); this is hardly surprising because DOS was copied from CP/M in about 1980.

CP/M comes/came in three main versions; 1.4, 2.2 and 3.1. v2.2 was the basis of MSDOS, while v3.1 evolved into DRDOS and OpenDOS / DR-DOS.

There were also 8086 and 68000 versions of CP/M. CP/M-86 evolved into DOS Plus, Concurrent DOS and REAL/32.

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Information

Articles

• A mini-howto explaining how to get DOS Plus 1.2 (CP/M-86 v4.1) running on your PC.
• Why CP/M? Dave Baldwin's USENET posting explaining his reasons for still using CP/M.
• A description of the Amstrad PCW16, based on seeing it demonstrated at the Crawley PCW Club.
• Building CP/M 3, thoughts on cross-compiling CP/M under DOS
• How to read CP/M discs on a PC
• "/" as the option character in CP/M.

Technical information

I hope to construct a HTML archive of all possible information about the various versions of CP/M. Some of the documents are my own; others are HTMLized versions of those at Oakland. So far, I have:

• Disc formats
• A summary of BDOS functions
• A comprehensive description of BDOS functions
• A comprehensive description of the Graphics System eXtension
• A partial list of functions provided by RSXs
• A description of the CP/M Plus System Control Block
• The I/O Byte in CP/M 2
• A list of the CP/M 1, 2 and 3 BIOS functions
• Exact file lengths under CP/M 3
• Layout of the File Control Block
• List of BDOS replacements
• CP/M and Year 2000 issues

Amstrad-specific

• A description of the Amstrad extended BIOS
• The Amstrad device driver (FID) interface
• Amstrad XBIOS internals

16-bit CP/M versions

• How CP/M-86 version numbers relate to the BDOS version numbers
• Some information about the CP/M-86 BIOS and FIDDs
• How DOSPLUS (CP/M-86 4.1) implements CP/M calls on a DOS filesystem
• Why the DOSPLUS .EXE loader doesn't work, and how to fix it.
• XIOS calls provided by DOSPLUS and Personal CP/M

Some file formats:

• .COM - CP/M 3 extensions
• .CMD, the CP/M-86 executable format
• .HLP, CP/M Plus Help file format
• .LBR, Library file format
• .REL, the object file format used by the M80 and RMAC linkers
• .IRL, the indexed version of a .REL library
• .PRL, CP/M and MP/M binary module. Also covers SPR, RSP, RSX, ...

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CP/M related links

What would the Web be without pages consisting entirely of links?

• USENET newsgroups:
  • The main CP/M newsgroup
  • 8-bit Amstrad computers - nearly all of these run CP/M in some shape or form.
• On the Web:
  • CP/M itself and many other Digital Research producats can be downloaded here.
  • IMS Developer Documentation for REAL/32 - a lot of it is relevant to earlier CP/M versions.
  • The Computer Journal homepage
  • Discus Distribution - distributors of CP/M-86, CP/M-68k and GEM software.
  • A link page for REAL/32.
  • Herne Data Systems' CP/M page.
  • Gaby's Computermuseum and CP/M-Userclub.
  • A page dealing with Multiuser DOS for industrial applications
  • CP/Net full documentation.
  • JFRACE - CP/M in a Java applet.
  • IMSAI Series 2 - a real live CP/M computer being produced in 2002.
  • Herb Johnson's S-100 site, plus
    • his CP/M and DRI Web pages, and
    • his How to start with CP/M
  • A resource site for Sam Coupe Pro-Dos (a CP/M 2.2 clone)
• FTP sites:
  • oak.oakland.edu, the biggest of them all. Check out the cpm, cpmug and sigm directories. The unix-c/cpm directory contains some portable tools to handle CP/M files. Alas! This site appears to have gone off-line owing to a disc crash.
  • ftp.mayn.de contains a mirror of most of what was at oakland, in its "archive" directory. The other directories mirror the CP/M source archives.
  • www.retroarchive.org contains some commercial CP/M software (some of which might be described as "abandonware"), and a copy of the Walnut Creek CP/M CDROM. The files from oak.oakland.edu which aren't at ftp.mayn.de can be found on the CDROM.
  • ftp.demon.co.uk contains some recent Amstrad-specific stuff, some miscellaneous utilities, and ZPM3/ZCCP - a free Z-System for CP/M 3.
  • ftp.zetnet.co.uk has similar contents to Demon, but some of my PCW programs are there as well.
  • ftp.update.uu.se has some DEC Rainbow-specific stuff and MicroEmacs.
  • soltrans.cr.usgs.gov can't be reached from here, so I don't know what's in it.
• Only vaguely CP/M related:
  • Amstrad PCW links.
  • Amstrad CPC web page.

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John Elliott 2 Jan 2000