CP/M-86
discontinued computer operating system for x86 processors
CP/M-86 is a discontinued version of the CP/M operating system that Digital Research (DR) made for the Intel 8086 and Intel 8088. The system commands are the same as in CP/M-80. Executable files used the relocatable .CMD file format. Digital Research also produced a multi-user multitasking operating system compatible with CP/M-86, MP/M-86, which later evolved into Concurrent CP/M-86. When an emulator was added to provide PC DOS compatibility, the system was renamed Concurrent DOS, which later became Multiuser DOS, of which REAL/32 is the latest incarnation. The FlexOS, DOS Plus, and DR DOS families of operating systems started as derivations of Concurrent DOS as well.
History
Digital Research's CP/M-86 was originally announced to be released in November 1979, but was delayed repeatedly. 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.
After discussions with Microsoft, IBM decided to use 86-DOS (QDOS), a CP/M-like operating system that Microsoft bought from Seattle Computer Products renaming it MS-DOS. Microsoft adapted it for the PC and licensed it to IBM. It was sold by IBM under the name of PC DOS. After learning about the deal, Digital Research founder Gary Kildall threatened to sue IBM for infringing DRI's intellectual property, and IBM agreed to offer CP/M-86 as an alternative operating system on the PC to settle the claim.
The public source identifies “CP/M-86” as discontinued computer operating system for x86 processors. This brief keeps that definition visible, then builds a research path around M-86, discontinued and computer.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Jul 17, 2026. The linked authority identifier is Q2706791. 1 of 1 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank. The first chronological checks are 1979.
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This entry incorporates text from “CP/M-86” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.