Multiuser DOS
family of CP/M- and DOS-compatible multi-user multi-tasking operating systems
Multiuser DOS is a real-time multi-user multi-tasking operating system for IBM PC-compatible microcomputers.
An evolution of the older Concurrent CP/M-86, Concurrent DOS and Concurrent DOS 386 operating systems, it was originally developed by Digital Research and acquired and further developed by Novell in 1991. Its ancestry lies in the earlier Digital Research 8-bit operating systems CP/M and MP/M, and the 16-bit single-tasking CP/M-86 which evolved from CP/M.
When Novell abandoned Multiuser DOS in 1992, the three master value-added resellers (VARs) DataPac Australasia, Concurrent Controls and Intelligent Micro Software were allowed to take over and continued independent development into Datapac Multiuser DOS and System Manager, CCI Multiuser DOS, and IMS Multiuser DOS and REAL/32.
The FlexOS line, which evolved from Concurrent DOS 286 and Concurrent DOS 68K, was sold off to Integrated Systems, Inc. (ISI) in July 1994.
Concurrent CP/M-86
The initial version of CP/M-86 1.0 (with BDOS 2.x) was adapted and became available to the IBM PC in 1982. It was commercially unsuccessful as IBM's PC DOS 1.0 offered much the same facilities for a considerably lower price. Neither PC DOS nor CP/M-86 could fully exploit the power and capabilities of the new 16-bit machine.
It was soon supplemented by an implementation of CP/M's multitasking 'big brother', MP/M-86 2.0, since September 1981. This turned a PC into a multiuser machine capable of supporting multiple concurrent users using dumb terminals attached by serial ports.
The public source identifies “Multiuser DOS” as family of CP/M- and DOS-compatible multi-user multi-tasking operating systems. This brief keeps that definition visible, then builds a research path around Multiuser, family and DOS-compatible.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Jun 29, 2026. The linked authority identifier is Q3867065. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1991, 1992, 1994 and 1982.
The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “Multiuser DOS” 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.