i stand corrected,  Ultrix _did_ run on the KA60. Looking thru the 
sources, i see comments that the ka60 support originally forked off of 
the KA650 support. 
Some interesting things in there include the fact that apparently the 
shoddy Qbus support was not the processor's fault but the way they 
designed it all to fit together; there's a regular CQBIC on the 
processor. The mbus options evidently were never intended to be changed 
or upgraded- they're identified in the bus initialization routines in the 
processor support module! (yuck!) 
It looks like they intended the Qbus to be the main means of expansion, 
and the mbus was just a way to attach a qbus. The mbus does not seem to be
a nexus interconnect, though, which makes this even kludgier. I think
mbus sucked more than they planned on it, and the Qbus support then was a 
failed idea. 

Isildur