Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!husc6!m2c!umvlsi!killoran
From: killoran@umvlsi.ECS.UMASS.EDU (Mik I Killoran)
Newsgroups: comp.sys.ibm.pc
Subject: IBM PC memory problems
Message-ID: <101@umvlsi.ECS.UMASS.EDU>
Date: 3 Apr 89 19:48:37 GMT
Reply-To: killoran@umvlsi.ECS.UMASS.EDU (Mik I Killoran)
Organization: University of Massachusetts, Amherst
Lines: 37

I have a very old IBM PC that has 256K of on-mother-board memory in the
form of rows of nine 64K chips.  There are four of these rows on the
mother board with the first being permanent and the last three rows
socketed in place.  I have installed a expansion memory board that
allows up to 384K additional memory bringing the total up to a sum of
640K.  Well, the memory that I bought for the expansion board had a mess
of BAD chips in the batch.  I set the system board (those two banks of
switches) to let the system know that it has 640K and I set the
expansion board to let it know there is 256K on the mother board.
Problems used to occur upon bootup with a message of #### 201 being
displayed on the screen.  I was told that the 201 meant that there was a
memory problem and the #### told where the bad chip was.  Using #### I
substituted new chips for defective chips and have gotten to the point
where the system will bootup.  BUT,

	Things only work if a version of DOS <=2.0 is used

	Sometimes big programs lock up

	There is occasionaly a error of PARITY CHECK # where # might be
             1 or 2   (when this happens the screen goes into a width of
                       fourty characters)

	A rather large spreadsheet of mine won't run giving the error
               internal error.


Things will work ok if I use DOS 2.0 and little programs.  But I would
really like to use what I have.  I have used Norton Utilities' SYSINFO
to check how much memory DOS reports and Active memory found, and both
say 640K.  Is there a way to find out which memory chips are bad?  If it
is a bad memory chip wouldn't it show up as a #### 201 error upon
booting up?  Any thoughts on my problem would really help me as I am
quite stumped.

			Thanks in advance,
				Michael Killoran