Strictly speaking, Coherent wasn't a V7 port – they wrote the code from scratch rather than using any of AT&T's code, and they never paid AT&T any Unix license fees.
AT&T was suspicious, but even after a careful investigation by Dennis Ritchie himself, they couldn't prove any of their code had been copied.
Given both the V7 source code and Coherent source code have now been released, you can compare them yourself and form your own opinion, if you'd like.
AT&T was suspicious, but even after a careful investigation by Dennis Ritchie himself, they couldn't prove any of their code had been copied.
Given both the V7 source code and Coherent source code have now been released, you can compare them yourself and form your own opinion, if you'd like.
V7 source code: http://minnie.tuhs.org/cgi-bin/utree.pl?file=V7
Coherent source code: http://minnie.tuhs.org/cgi-bin/utree.pl?file=Coherent4.2.10