Need Docs for XT RAM Board...
fireflyst at earthlink.net
Thu Nov 9 10:02:10 CST 2006
I did the mod Tony spoke of to mine about 2 years ago and have had no
According to several different books, all original IBM XT boards have
Are you SURE this is an XT board, and not a PC board?
I apologize for the earlier message by the way, I misread that your board
From: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org]
On Behalf Of Al Hartman
Sent: Wednesday, November 08, 2006 9:46 PM
To: cctalk at classiccmp.org
Subject: Re: Need Docs for XT RAM Board...
I'll take a look. But I think all four rows are soldered in.
> If it's an IBM XT mainboard, there's an easy way to do this (and not use
> up any expansion slots).
> Put 41256 chips in banks 0 and 1, and 4164s in banks 2 and 3 on the
> mainboard. Put a 74S158 (or 74F158) multiplexer chip in the emptu socket
> at the front right, pointing the same way as the chips around it. Set the
> DIP switches for 256K RAM, and solder a jumper wire between pads E1 and
> That's it. You have a 640K XT mainboard.
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