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Path: utzoo!decvax!microsof!uw-beaver!cornell!vax135!floyd!harpo!seismo!hao!hplabs!sri-unix!GILLMANN@USC-ISIB
From: GILLMANN@USC-ISIB@sri-unix.UUCP
Newsgroups: net.micro.pc
Subject: XT Memory Add-on
Message-ID: <1544@sri-arpa.UUCP>
Date: Mon, 23-May-83 20:51:00 EDT
Article-I.D.: sri-arpa.1544
Posted: Mon May 23 20:51:00 1983
Date-Received: Sat, 28-May-83 00:54:24 EDT
Lines: 27

From:  Dick Gillmann 

I tried filling out the motherboard memory on my XT by buying 64K
chips and putting them in.  No matter how I set the switches, it
didn't work.  In fact, the XT acted just like they weren't there; it
checked the memory out to 128K and then booted normally.  Running the
diagnostics gives one of those cryptic error msgs that the book says
"replace the motherboard" on.  So I removed the chips and everything
went back to normal.

Not being a hardware type, I'm pretty well stumped.  The chips I put
in were Mitsubishi plastic M5K4164NP-15 150ns RAMs.  I'm sure I put
them in the right way and they were new chips.  Any help would be
appreciated.

Dick

P.S.  As near as I can determine, here are the XT switch meanings:

1   Normally OFF       (ON, loop post)
2   Normally ON        (reserved for co-processor)
3-4 Motherboard Memory (11=64K, 01=128K, 10=192K, 00=256K)
5-6 Displays           (01=color 40, 10=color 80, 00=mono or both, 11=none)
7-8 Floppy Drives      (00=4, 10=3, 01=2, 11=1)
 
[Thanks to Shostak@SRI-CSL and JOHNSOND.IBM-SJ@Rand-Relay.]
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