[pjmlp]

According to some sources, which I sadly cannot point out to, just vague memories from somewhere, so take it with a grain of salt.

Early MS-DOS development used to be done from those Xenix environments, they would cross-compile to PCs, until later on, did they migrate to MS-DOS directly.

Most likely around MS-DOS 5, given the MS-DOS 3.3 resources and how MS-DOS 4 development went.

On the other hand, there is the what-if alternative universe of what would have happened had they kept Xenix around.

[dboreham]

Hmm. Wasn't it done on a dec-10?

[kragen]

you're thinking of basic-80, which gates and allen (and davidoff) did (in 01976?) on the dec-10 at harvard, but we're talking about qdos, which tim paterson did in 01981 at seattle computer products before selling it to microsoft

[dboreham]

Ahhh yes. The great distance of time made me forget that DOS is actually relatively new.