4 Mb SIMMS

[Shoshana Abrass]

  We've started having a weird problem with our 4 Mb SIMMS. Background:
  We're using 100% Toshiba chips. Some of our simms were built by 
  Kingston, some of them were built by Toshiba - but it doesn't make
  a difference as far as our problem goes.  We've been using the 4 Mb 
  SIMMS in our 4D 25's since at least september and currently have them
  in 18 machines.

  At first the simms worked fine. But then a few times I noticed that
  when I powered down a machine, I would get an error on startup. This
  error occurs during power-on diagnostics and flashes on the screen
  *very* briefly (but can be stopped with <ctrl>-S). After the error, 
  the machine won't boot and an hinv at the PROM shows 0 memory. The
  entire message is shown below.

  The weird part: The problem doesn't mean that the hardware is bad. At
  first we panicked and called the hotline; they replaced the e-mod and
  things did work better. But then we realized that by just wiggling the
  simms, we could make the problem go away. I've now done this more than
  a dozen times on various machines . The problem always occurs at boot
  time - the machine runs without problems once it's up. Wiggling or, at 
  worst, removing and re-installing the simms always fixes the problem.
  I guess that the physical fit between some 4 Mb simms and some iris 
  memory slots is a bit loose or otherwise imperfect.

  I'm posting to the net because (1) others may have this problem some
  day (2) I'm wondering if anyone has had this problem and found a 
  permanent fix? (3) I thought SGI gurus might have some insight into
  the error message.

-------------
EXCEPTION: <vector = NORMAL>
Exception pc: 0xbfc00e0c
Cause register: 0x1c <CE=0, EXC=DBE>
Status register: 0x88004 <CM, IM8, IPL=7, IEp>
Error Addr register: 0x400000
Local I/O interrupt register: 0xbf <GE, VME ACFAIL, VERTICAL>
Parity error register: 0xe4 <CPU>
Registers (in hex): 

[many registers listed]
------------

  -shoshana
  shoshana at pdi.com
  pdi!shoshana at sgi.com

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