Concurrent Controls Multiuser DOS

Liam Proven lproven at
Sat Oct 3 19:02:45 CDT 2020

On Sat, 3 Oct 2020 at 18:14, Jonathan Haddox via cctalk
<cctalk at> wrote:
> I'm researching Multiuser DOS out of my own interest.  A version made by Concurrent Controls specifically.  However, I have been unable to find documentation on it to satisfy my curiosity on how it works and how it is configured.  They must have somehow broken the 640K barrier or virtualized each user session, I'd like to understand it better.  What were it's limitations, I'm guessing that each user didn't get direct access to hardware.  Anyone out there have a document or experience with it?

It's just one fork of the old DR Concurrent DOS/386, descended from
Concurrent CP/M. The Wikipedia article is a good start:

I say this with slight bias as I wrote a chunk of it. Yes, I had some
experience with it, installing and supporting it on customers' systems
in the late 1980s.

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