segmented memory models

[Brian L. Stuart]

> And AFAIK there is no MMU for the PDP11/20 (the first PDP11 

Not as a product.  However, lo these many years ago (neigh
on to 3 decades), I was shown an object that consisted of
numerous DEC modules and told that it was one of three MMUs
that had been built for the 11/20.  Since we also had an
11/20 there, it was at least plausible.  To my knowledge,
it was later lost to a great clean-out.  Now, I have no
idea whether it really was an 11/20 MMU, but I do recall
a while back coming across a mention of what sounded like
an experimental MMU for it.  So such a thing did exist
in legend and myth...

BLS