Re: DECstation 2100: power trouble?

>> [...]  Perhaps I was wrong about which slots were bank 0; [...]
> Slot numbers are given on the PCB, on the PSU side, and I reckon are
> not in order.  Slots 1 & 2 always have to be occupied and modules
> installed in pairs.

I'll have to have a look when I next pick this up, then.

>> So I started a (diskless) rebuild of the 1.4T world.  [...]
> It would help if the kernel actually provided the bus addresses
> causing the failure, i.e. the contents of $a0 and $s2 respectively,
> translated to the corresponding physical address.  That's
> straightforward to do (but someone has to write such code of course).

I may want to build a MIPS emulator, to build code on.  Not sure
whether I'd make it a userland-only emulator, like my SPARC emulator,
or a full-machine emulator, like my VAX emulator - the former seems
more likely; I could likely steal large parts of the SPARC emulator
verbatim.  (I suspect SIMH includes a 2100 emulator.  I may take
another run at getting it working at some point; I'm pretty sure I
tried to build SIMH and ran into some problem that stopped me then.)

I've also discovered that build.sh-style cross-building came in earlier
than I thought (with 1.6), which may help - I could cross-build 1.6.2,
which would likely be quicker and easier than writing an emulator.

> Have built-in console memory tests (e.g. `t a' I mentioned
> previously) never shown any failures?

No, but I haven't run them very often.

>> So I put the machine back together [...] and have stopped fussing
>> with it for now; I'm finding I don't have the frustration tolerance
>> these days to handle dealing with broken hardware, especially subtly
>> broken hardware.
> I think a marginal PSU might cause memory errors at load spikes.  At
> least replacing output filter capacitors ought to cause no
> regression.

Fair enough.  I also can look up details and have a stab at putting
together something entirely modern that, while not truly a
_replacement_, could at least power the machine.

> NB I've now located a local copy of the maintenance guide too, [...]
> should you wish to continue experimenting with your little system.

Thank you!  I've snaffled a copy of that now and will be giving it a
read-through.  It's all but certain to contain useful info.

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