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From: lstowell@pyrnova.pyramid.com (Lon Stowell)
Newsgroups: comp.sys.ibm.pc.misc,comp.misc
Subject: Re: Help! Memory Parity Problem!!
Message-ID: <138527@pyramid.pyramid.com>
Date: 21 Dec 90 20:26:22 GMT
Sender: daemon@pyramid.pyramid.com
Reply-To: lstowell@pyrnova.pyramid.com (Lon Stowell)
Organization: Pyramid Technology Corp., Mountain View, CA
Lines: 66

In article <1990Dec20.185019.29981@portia.Stanford.EDU> shedevil@portia.Stanford.EDU (Annie) writes:
>Help!
>
>Here is what my computer does:
>
>Every so often when I boot it up, *after* displaying the numbers which show
>it running up to its 640k, it will go into set-up...it seems to think
>that I have changed the size of the memory (which is actually at 640k).  
>Sometimes the set-up display shows 520k memory,, sometimes 640, and I
>think also sometimes 560.
>
>I realize this sounds confusing, but this is what it is doing. 
>
>And SOMETIMES it will just freeze up and display this error message:
>
>"Memory Parity Failure".

You don't give a brand name, but it looks like your set-up
memory is faaaaaaaaaaaaaaaading.

Most AT clones, etc. have a non-volatile storage for set-up info
to retain configuration settings when power is switched off.

Exactly how this is done depends on the mfgr... some use the
true non-volative EEPROM storage (no battery required when power
is off) and some use a low-powered RAM with a (large) capacitor
or a battery.

If your battery is getting low, your machine will intermittently
lose the set-up info when power is turned off.   The longer
power is off, the more likely this will happen.

If this set-up info is lost, the machine will typically enter
set-up mode...with the default setting typically of 500 or so
Kbyte of RAM.   It may even log memory parity errors, either
from the set-up RAM or mistakenly from main memory.

These batteries vary in lifetimes...size, shape, and whether or
not you can change them w/o special tools.  

If you or a friend are electronic techie inclined, open the case
and look for a battery.  Typically they look like small stubby
flashlight batteries or are coin shaped like a watch battery.

Try a new one....and DON'T handle the coin-shaped units with
bare fingers...it leaves a thin coating of skin oil on them
which causes premature failures.   (You can get special finger
protectors for handling these, but a DRY UNLUBRICATED cheap
condom works just as well...)

Some times you can do a temp fix by removing the battery and
rubbing the end (flashlight style) or sides (coin style) on a
piece of newspaper, then replacing...watching the fingers...

I would fix this loss of set-up info before worrying about
memory errors...both may be related.  (You MIGHT have a
defective power supply or mother board, but I'd try the quick
fix first...)


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