“Started as”
Yeah, no. Yes Xenix was a thing but it would be incorrect to say that it ever was their main product.
I don’t think anyone has ever hinted on that NT has a unix code base except for some “borrowed” networking code from bsd.
it would be incorrect to say that it ever was their main product.
They made several full versions of it… It was not simply a one off product.
While Xenix 2.0 was still based on Version 7 Unix,[30] version 3.0 was upgraded to a Unix System III code base,[12]: 9 [31][32] a 1984 Intel manual for Xenix 286 noted that the Xenix kernel had about 10,000 lines at this time.[10]: 1–7 It was followed by a System V R2 codebase in Xenix 5.0 (a.k.a. Xenix System V).[33]
Also,
Microsoft’s Chris Larson described MS-DOS 2.0’s Xenix compatibility as “the second most important feature”.[38] His company advertised DOS and Xenix together, describing MS-DOS 2.0 (its “single-user OS”) as sharing features and system calls with Xenix (“the multi-user, multi-tasking, Unix-derived operating system”), and promising easy porting between them.[39]
So they were simultaneously created AND interoperable (from a program development perspective). This was a full fledged item.
Edit: to elaborate a little better. If they were simultaneously developed… and interoperable. And one item is Unix-based outright. Then it’s safe to say that the other item (MS-DOS) in this case is also pretty steeped in Unix roots.
