[TUHS] First Unix-like OSes not derived from AT&T code?

[Rob Pike]

The folks at Bell Labs were asked to figure out if Mark Williams had copied
Unix directly or via too much knowledge already obtained, or whether it was
truly a clean room recreation. I don't remember all the details, but it
became clear after a while that it was indeed a reasonably clean rewrite.

This was done by looking for corner cases that were an accident of the
original implementation and would be unlikely to appear in a version
created separately. One detail that did stick with me was the discovery
during this process that ppt, the paper tape simulator, mispunched a
letter, I think "R", but the Mark Williams version did not. Was that
compelling? Not on its own, but it was funny and memorable.

-rob


On Sun, May 1, 2022 at 9:46 PM Ron Natalie <ron at ronnatalie.com> wrote:

> Mark Williams Coherent was one I worked with on the PC many years ago.
>
> > On May 1, 2022, at 11:34, Andrew Warkentin <andreww591 at gmail.com> wrote:
> >
> > What was the first "clone" functional Unix (i.e. an OS not derived
> > from genetic Unix code but highly compatible with genetic Unix)? Idris
> > is the earliest such OS of which I am aware (at least AFAIK it's not a
> > genetic Unix), but was it actually the first? Similarly, which was the
> > first "outer Unix-like" system (i.e. one with strong Unix influence
> > but significantly incompatible with functional Unix)? Off the top of
> > my head the earliest such system I can think of is Thoth (which
> > predates Idris by almost 2 years), but again I'm not sure if it was
> > actually the first.
>
>
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