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.

Concurrent DOS 386 uses about 200K of conventional memory, much more than MS-DOS. BYTE said that with the software's minimum requirement of 512K RAM "all you can do is admire the system prompt", and estimated that 1MB RAM in addition to the base 640K allows for using three major applications like Microsoft Word or Multiplan.

Concurrent DOS 6.0 represented also the starting point for the DR DOS family, which was carved out of it.

Known versions include:

  • DR Concurrent PC DOS XM 5.0 (BDOS 5.0)
  • DR Concurrent DOS XM 5.0 (BDOS 5.0, October 1986)
  • DR Concurrent DOS XM 5.1 (BDOS 5.1?, January 1987)
  • DR Concurrent DOS XM 5.2 (BDOS 5.2?, September 1987)

</references>

Further reading

  • former Intelligent Micro Software (IMS) website (vendors of IMS Multiuser DOS, IMS REAL/32, and REAL/NG)
  • former Logan Industries (LLI) website (IMS REAL/32 US distributor up to 2002-05-01)
  • former Concurrent Controls website (CCI Multiuser DOS)
  • Applica, Inc. website
  • former Aplycon Technologies, Inc. website

<!-- Category:Digital Research-->