David Brownlee <abs@netbsd.org> wrote about IBM/RT and AOS.
  
> I'm afraid that is not a platform we currently support.
> If I recall correctly IBM did make a BSD port available
> as 'AOS' (Academic Operating System), and you may be
> able to find a copy of that.

Right, they had 4BSD for IBM/RT (not AIX; not sure the relationship
with CMU/ITC) Friends of mine used them at their Univ (they even had
source code of AOS) I saw a bunch of them was thrown away many years
ago.  Slow, yet, impressive machines.

One of my favarite book by R. Dewar comments about IBM RISC as;

 Up this point, IBM has not succeeded in taking commertial advantage of
 this technology.  The main effect of RT introduction seems to have
 been to confer legitimacy on other manufactures' more successful use
 of RISC chips in engineering workstations.

Please note that the book was written before the introduction of POWER
processor product line w/ AIX, which was a large impact to (Japanese)
UNIX industry.  (They consumed electricity as well contrary to their
names, ;-)

Tohru Nishimura