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From: gillies@m.cs.uiuc.edu (Don Gillies)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Mac II - Floppy upgrade
Message-ID: <1991Apr23.013313.16729@m.cs.uiuc.edu>
Date: 23 Apr 91 01:33:13 GMT
References: <3070@sparko.gwu.edu> <4943@dftsrv.gsfc.nasa.gov> <17613@venera.isi.edu> <4959@dftsrv.gsfc.nasa.gov>
Organization: University of Illinois, Dept. of Comp. Sci., Urbana, IL
Lines: 20


There are problems with II, and IIx, and no upgrade can fix them.
These machines simply cannot accept standard 4Mb simms -- the ones
using 8 * 4Mb DRAM chips.  They can accept 4Mb simms built from 32 *
1Mb DRAM chips.  The 4Mb DRAM chips have a special "test" wire, which
is brought out through the simm connection, and which the Mac II/IIx
logic board does not handle correctly at boot time.  The 1Mb DRAM
chips have no such test wire, so they work correctly with the II/IIx.

This is from the Apple Tech Note on DRAM installation and 32-bit
cleanliness.

Don Gillies	     |  University of Illinois at Urbana-Champaign
gillies@cs.uiuc.edu  |  Digital Computer Lab, 1304 W. Springfield, Urbana IL
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"WAR!  UGH! ... What is it GOOD FOR?  ABSOLUTELY NOTHING!"  
	- the song "WAR" by Edwin Starr, circa 1971


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