[skissane]

Would the original authors of Unix agree with your opinions on how to define the term?

Does AT&T's c. 1980 port of Unix to run on top of IBM's TSS/370 mainframe operating system [0] count as a real Unix? It appears that Ritchie did think it was a Unix, he linked to the paper from his page on Unix portability [1].

So is your definition of "Unix" broad enough to include that system? If not, you are defining the term differently from how Ritchie defined it; in which case I think we should prefer Ritchie's definition to yours. (McIlroy's maxims are explicating the Unix philosophy, but I don't read him as saying that systems which historically count as Unix aren't really Unix if they fall short in following his maxims.)

[0] https://www.bell-labs.com/usr/dmr/www/otherports/ibm.pdf

[1] https://www.bell-labs.com/usr/dmr/www/portpapers.html

[caslon]

> McIlroy's maxims are explicating the Unix philosophy

This is why I used the quote, not for this reason:

> but I don't read him as saying that systems which historically count as Unix aren't really Unix if they fall short in following his maxims.

I'd say yes, a port of v7 is fine, because it's not meaningfully more complex. It can still be comprehended by a single individual (unlike FreeBSD, Linux, everything currently called Certified Commercial UNIX trademark symbol, etcetera).

[skissane]

> I'd say yes, a port of v7 is fine, because it's not meaningfully more complex

I think AT&T's port of V7 (or something close to V7, I guess it was probably actually a variant of PWB) to run on top of TSS/370 really is meaningfully more complex because in order to understand it you also have to understand IBM TSS/370 and the interactions between TSS/370 and Unix.