PDP-11/45 RSTS/E boot problem
Noel Chiappa
jnc at mercury.lcs.mit.edu
Sun Jan 20 15:29:09 CST 2019
> From: Paul Koning
> It checks if the bits 007750 are active in the parity CSR, if so it
> takes that to be an address/ECC parity CSR.
That's odd; those are the 'error address' bits. Maybe there's an assumption
that the sweep of memory to size it will have caused a parity error from
garbage in DRAM at startup? (If so, I wonder if it would work on a machine
with all core? :-)
> It figures out the CSR to memory association by going through memory in
> 1 kW increments ... This should set bad parity, and it scans all the
> CSRs to see which one reports an error ... If no CSR has that set, it
> concludes the particular block is no-parity memory.
Oooh, pretty clever - good workaround for rhe undefined relationship between
CSR's and memory.
If I added parity support to V6, I'd be tempted to do it with a
hand-configured table - devices are all manually configured anyway in V6, so
I'd be continuing a theme... :-)
Noel
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