CP/M-86 was a version of the CP/M operating system that Digital Research made for the Intel 8086 and Intel 8088. The commands are those of CP/M-80. Executable files used the relocatable .CMD file format. It was later reworked to become MS-DOS compatible and renamed to DR-DOS.
CP/M-86 and the IBM PC
When IBM contacted other companies to obtain components for the IBM PC, the as-yet unreleased CP/M-86 was its first choice for an operating system because CP/M had the most applications at the time. Negotiations between Digital Research and IBM quickly deteriorated over IBM's non-disclosure agreement and its insistence on a one-time fee rather than DRI's usual royalty licensing plan.
A given version of CP/M-86 will have two version numbers. One applies to the whole system and is usually displayed at startup; the other applies to the BDOS kernel. Versions known to exist include:
- CP/M-86 for the IBM Personal Computer Version 1.0 (BDOS 2.2) - January 1982 - Initial release for the IBM PC.
- CP/M-86 for the IBM Personal Computer Version 1.1 (BDOS 2.2) - March 1983 - Hard drive support was added.
- CP/M-86 Plus Version 3.1 (BDOS 3.1) - October 1983 - Released for the Apricot PC. Based on the multitasking Concurrent CP/M kernel, it could run up to four tasks at once.
- Personal CP/M-86 Version 1.0 (BDOS 3.1) - November 1983 - Released for the Siemens PG685.
- Personal CP/M-86 Version 3.1 (BDOS 3.3) - January 1985 - A version for the Apricot F-Series computers. This version gained the ability to use MS-DOS formatted disks.
- Personal CP/M-86 Version 2.0 (BDOS 4.1) - 1986 or later - Released for the Siemens PC16-20. This is the same BDOS used in DOS Plus.
- Personal CP/M-86 Version 2.11 (BDOS 4.1) - 1986 or later - Released for the Siemens PG685.
All known Personal CP/M-86 versions contain references to CP/M-86 Plus, suggesting that they are derived from the CP/M-86 Plus codebase.
There is a patch for Version 1.1 that allows it to run on AT-compatible hardware.