I'm confused about this whole thread.  I really thought that there was
another entire OS/2 operating system (not from IBM) that people were
talking about.
The early versions IBM OS/2 ran on the 80286 processor.  Later versions
required a 386 processor.  There was an effort in IBM to put it on
PowerPC derived boxes - I know people who worked on that, and was
actually jealous that I didn't get on that project.  (In retrospect that
was not such a bad thing.)
How on earth does something like IBM OS/2 ever get ported to a PDP-11?
That doesn't seem feasible.  I'd have thought that I would have heard of
such a thing before this thread.
Mike