27 Jul
2012
27 Jul
'12
1:15 p.m.
I'm curious if anyone has ever debugged an QBUS MSV11 board.
I have one which appears to have a bad memory location - a single bit
error. I assume this means there
is one bad dram chip. But I've never debugged a memory board like this
before.
Is it possible to figure out which chip is bad? (it seems obvious the
answer is yes, but how?)
I'd look at the schematics. IIRC the MSV11 uses 16K*1 DRAM chips, so each
DRAM contains a particular bit of the word for 1/4 of the words on te board.
From the schematic, you can see which DRAMs (there will
be 4 of them)
handle the bit that's failing. Then you look at the address
decoding
circuitry to see which of those RAMs contains the failing location. And
change that chip.
-tony