23 Apr
2016
23 Apr
'16
2:03 p.m.
First of all you might be able to run some SRAM
diagnostics yourself,
either
from the console (if it has a tool for this; at worst
you could poke at it
manually with deposit/examine commands, but the complicated flashbus
access protocol will make it a tedious task unless there is a way to
script it)
I have been trying to work out how to do that very thing. I don't think
there is quite enough info in the technical manual.
or
from the OS (can't help how to do this from VMS; under Linux you could
mmap(2) /dev/mem at the right address and then poke at it with a little
program doing the right dance to get the flashbus access protocol right),
to
see if it shows any symptoms of misbehaviour.
If necessary I should be able to install linux, but still, working out the
address doesn't seem trivial.
To experiment with DROM you might be able to find a DIP-to-PLCC socket
adapter, pinouts for ROMs are pretty standard I believe.
I have ordered an adapter so I can read the ROM. Would be good, as you
suggest, to read someone else's to compare...
A ROM emulator
might help too if you can get your hands on one, second-hand units are not
exactly expensive nowadays as they went out of favour it would seem.
Overall, hard to say which failure case would be better (or worse). It
looks to
me like at this point you have several options to
proceed with.
Good luck with your investigation and recovery! I wish I had one of
these
machines, they are sweet and they run Linux out of the
box. ;)
Maciej
Many thanks for all your help today!
Regards
Rob