CP/M Main Page
Last updated: 15 June 2012
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.
- 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
- Mallard BASIC miscellany
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
- A description of the Amstrad extended BIOS
- The Amstrad device driver (FID) interface
- Amstrad XBIOS internals
- DISCKIT development
- GSX driver development
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, ...
What would the Web be without pages consisting entirely of links?
- USENET newsgroups:
- On the Web:
- CP/M itself and many other Digital Research products 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
- 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:
John Elliott 2 Jan 2000