PDP-11/45 RSTS/E boot problem

Noel Chiappa jnc at mercury.lcs.mit.edu
Mon Feb 11 07:04:29 CST 2019

    > From: Fritz Mueller

    > If, as you are suspecting, we find damning evidence pointing
    > specifically to the RK11

I got an update from Fritz. As you all will recall, the problem seemed to be
a corrupted 'pure text'. So the question was 'when was it damaged, and how'.

After some confusion caused by different OS images (the 'Ritchie' and
'Wellsch' distros), he managed to get a look at the text in main memory after
it was first read in from the file system, and before it was swapped out (it
was showing up damaged after a swap out/in cycle); it looked good at that
point. The copy written out to the swap disk however, not so good.

A look at the RK11 registers after the swap-out showed an anomaly; something
about the extended memory address bits? (Maybe a multi-block transfer than
crosses a 64KB boundary? That would explain the address sensitivity we were
seeing.) Hopefully he'll track it to its lair shortly.

We also need to characterize exactly what the fault is, because the DEC RK11
diagnostics weren't finding it, so it seems the diagnostic suite could use an


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