Quoting Wesley Parish <wes.parish(a)paradise.net.nz>:
Does anyone know anything more about it than I do,
which is that it was a
rebadged 4.3BSD for the RT platform? And stands for Academic Operating
System?
The first version of AOS was basically a straight port of 4.2BSD.
The second version was a straight port of 4.3BSD. As a friend of
mine once described it, "With all the bugs, just like you remember
them!" (since the initial releases were done without any of the
publicly available fixes - though many of those were added over
time)
Aside from the support for "minidisks" (a way of dividing up a
hard drive that was compatible with AIX 2.x for the RT, sort
of like DOS/Windows "FDISK" partitions....), and support for some
RT-specific devices like the ACIS Experimental Display, there
really wasn't much remarkable about it, as such - just another
port of 4.xBSD ...
--Pat.