Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!ames!ncar!tank!eecae!upba!dsndata!unocss!mlewis
From: mlewis@unocss.UUCP (Marcus S. Lewis)
Newsgroups: comp.sys.zenith.z100
Subject: Z-100 memory problems
Keywords: parity errors
Message-ID: <808@unocss.UUCP>
Date: 23 May 89 10:49:44 GMT
Organization: U. of Nebraska at Omaha
Lines: 27

I can't believe I am having these problems!  I just upgraded my old-MB
Z using the Wideman method to 768K.  This was to free up my UCI board
for another system, and I went from 704K to 768K in about 3 hours.
No problem.  When I was using the UCI board, I had very occasional 
parity/buss errors that shut the system down.  Very annoying, but 
completely eliminated by using a 200K Ramdisk.  I loaded 200K of
stuff in there and never had a problem.  This doesn't work any
more.  Now I am getting parity errors at random intervals, but at a
fairly high frequency.  Since my wife and kids try to use this thing,
this is totally unacceptable.  What's going on.  I have tried to 
disable parity by outputting various values to port 0FCH, the memory
control latch, all of which so far have resulted in truly bizarre
behaviour and an immediate need to reboot.  The memory system passes
multiple passes of both the Zenith diagnostics and the ROM Monitor
memory test.  I had a single error on Sunday, not repeated, but that
whole bank got replaced anyway.  The Zenith diagnostics won't touch
the parity stuff, since I don't have a Z-205.  I get a parity error
immediately on that test for banks 3-6.  HELP!  The 64K chips I 
pulled were 200ns parts and the 256K chips installed are 150ns, so 
I don't think response time is the problem.
Marc

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