coatta@utcsri.UUCP (05/07/87)
I am another individual who has the REV A board problem. I happily
constructed the Squeeze-RAM (which took about 4 hours, and is quite
easy to do -- if they'd only precut those socket strips -:), and
the opened my computer to find that I had REV A boards. I installed
the Squeeze-RAM, and booted. Well, the system came up, and so I
thought all was well, but after about 2 or 3 minutes I got the
"bit decay" on the screen and the system died. I have gone over
the board checking for bad solder joints, and reseating all the chips
but to no avail. I performed some experiments on the board as well:
(1) Booted under 1.1 and did NOT do an ADDMEM. Thus the system knew
nothing about the extra memory. Ran a memory test program. Everything
goes fine for about 20 minutes, and then poof, the system gurus. It
is NOT the memory test program I can guarantee that. This is relatively
repeatable -- that is the system always behaves the same way, just the
ETG (estimated time to Guru) varies. The reason that I say it is not the
memory test program failing is that the same behaviour can be observed
by just letting the system sit for 10-20 minutes. The memory test program
however, indicates no errors in the memory up till guru time.
(2) Removed 256K Chip RAM cartridge, and switched to only using 512K of
the Squeeze RAM. Booted under 1.2 and now the system lives for about
20 minutes rather than 2.
I haphazard a guess based on this info, that the presence of the
Squeeze-RAM affects line loading, or signal timing of some stuff headed
to the daughter board, and that this causes a daughter board malfunction
with a low probability. The first test suggests that it is not
Squeeze RAM memory failure which causes the Gurus, the second test
suggests that line loadings or something similarly analog that
causes the problem.
So anybody out there in NetLand got any suggestions? I'd really
like to have the extra Meg floating around (I'm back to a 512K
system in the meantime) -- It was really great for the 2 or 3 minutes
that I could use the machine before it gurued :-)
Terry Coatta
Dept. of Computer Science, Univ. of Toronto, Canada M5S 1A4
{allegra,cornell,decvax,ihnp4,linus,utzoo}!utcsri!coatta
coatta@csri.toronto.cdn
`What I lack in intelligence, I more than compensate for with stupidity'