It looks like
the question boils down to either "how did that part of
the binary get to that part of memory?", or "how did we end up
executing out of that part of memory?"
More the former, I think...
Noel, is it possible for you deduce where Unix _should_ be placing these
"bad" bits (from file offset octal 4220)?
Maybe a comparison of addresses where the bits should be, with addresses
where the "bad" copy ends up, could point us at some particular failure
modes to check in the KT11, CPU, or RK11...
--FritzM.