IBMPC 640K upgrade on motherboard

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#11089

From: Kerry Kanbe
Date: Fri, 14 Jun 1991 16:44

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I'm an owner of an ancient 256K motherboard IBM-PC.  I've heard that this
motherboard originally had the hooks designed into it to allow 640K of RAM
on the motherboard.  This is supposedly accomplished by replacing two banks
of 64K chips (9 chips per bank) with 256K chips (41256), plopping a 74LS158
into an existing socket and jumpering something somewhere.  At approximately
$2 for each of these chips, I'd be looking at ~$40 to upgrade from 256K to
640K.  This is below my cost pain threshold for upgrading an obsolete machine.
Does anyone out there have any experience or knowledge of this procedure?  If
so, I'd appreciate any replies via e-mail.
-- 
Kerry Kanbe				email: kerryk@oakhill.sps.mot.com
Motorola High End MPU Design		phone: (512) 891-3040
Austin, TX

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Message-ID: <1991Jun14.164449.1213@oakhill.sps.mot.com>

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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!oakhill!kerryk
From: kerryk@oakhill.sps.mot.com (Kerry Kanbe)
Newsgroups: comp.sys.ibm.pc.misc,sci.electronics
Subject: IBMPC 640K upgrade on motherboard
Message-ID: <1991Jun14.164449.1213@oakhill.sps.mot.com>
Date: 14 Jun 91 16:44:49 GMT
Organization: Motorola Inc.  Austin, Tx.
Lines: 13