[rescue] SPARCBook 3gx

Justin Haynes justin at justinhaynes.com
Tue Mar 15 23:20:05 CDT 2011

My SPARCBook 3gx is fully functional, but i am having difficulty maxing out
the RAM.

the 2x32MB of ram I have works just fine, but the 2x64MB of ram I ordered is
not working fine at all. I'm wondering if any of you can offer any tips or
explain the behavior I'm seeing.

when both 64MB memory modules are installed for what should be 128MB RAM,
only 32MB is reported and only in the first slot.  These must be installed
in pairs however as they are SIMMs

These are 64MB 60ns parity 1" (low profile) 72-pin SIMMs.   (i.e a 36x16 or
'true parity' or '9-chip SIMM).

I can swap slots and I still get the same behavior.  As expected, if you
only put one SIMM in one of the slots, the machine will not initialize.

the machine will actually boot up and show only 32MB of RAM when the pair of
64mb SIMMs is installed.  This suggests to me that even though it is
reporting 32MB in one slot, it is actually only seeing 16MB from each SIMM
or 1/4 of the memory.

On the 32MB SIMMs that work correctly, there are 9 chips on each side of
each SIMM for a total of 36 chips.  On the 64bit SIMMs, there are only 4
larger chips per side and 2 smaller ones in the center on each side.

What could be causing this?

I can provide video to show everything, but I wanted to get feedback first
if someone already had an answer, idea, or explanation.



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