DOS code in CP/M? Revisited...

Liam Proven lproven at
Fri Jul 15 12:30:46 CDT 2016

On 14 July 2016 at 20:50, Chuck Guzis <cclist at> wrote:
> Everyone seems to forget about the work-alikes, such as TPM for the
> Epson QX-80.

True. And there was Pro DOS for the SAM Coupé:

ZCN for the Amstrad NC series:

And probably others.

> GEM for the Atari ST is essntially a clone of MS-DOS functionality for
> the 68K with a graphics enhancement tacked on.  Yet I've never heard any
> accusations that DRI "pirated" MS-DOS.

Not GEM as such -- it's the GUI layer. But ST GEM ran on a kernel
called GEMDOS, which was a sort of hybrid of CP/M-68K and DR-DOS: a
68000 kernel but with MS-DOS like API compatibility.

Written by DR and licensed from them by Atari.

So, a better comparison would be DR-DOS. I think nobody ever claimed
that DR stole MS-DOS source code, though. It was clean-room
reverse-engineered, and had some different internal data structures,
which manifested in a (very very few) compatibility problems.

However, the accusation is that MS -- or SCP -- did actually use CP/M
source code in creating QDOS.

It's not that QDOS' design was copied from CP/M, which it was --
that's already been admitted. It's that QDOS contained appropriated
CP/M source from DR.

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