IIRC, Morrow Designs biggest, baddest S-100 machine (used a switching PS!)
could run CP/M but with a special boot ROM (on the backplane with serial I/O
I believe) also ran UNIX System V substituting a 68000 CPU board for the
usual Z80. That was the Tricep I believe, which came out around 1984.
Bob Stek
Saver of Lost Sols