Another Coherent fan here. That was an awesome system. And for once: awesome documentation. The Coherent book long outlived the Coherent system for me.
I totally agree! I still remember the cover of that book, with the picture of the shell on it. I learned most of the "POSIX" APIs from it before I moved to Linux.
I still have all my Coherent manuals and disks. I still referenced the manual for years after I moved on to Linux.