Coherent: Unix variant for DOS compatible PCs (1994) [pdf]

Article note: On one hand, Coherent was one of a spate of interchangeably doomed commercial UNIXes of its era, and not a particularly early one. On the other hand, there's a bunch that's interesting about it. They had excellent, exaustive, user-respecting documentation of a kind that just doesn't exist anymore. The fact that there were a bunch of serious operating systems in the late 80s and early 90s, and essentially none since tells us something (horrible) about the hockey-stick graph on platform complexity. It's fascinating that there were a ton of UNIX-likes and no other platform has had that kind of profusion. Did the UNIX folks really hit that good a local maxima? Can we characterize that?