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From: dwb@apple.UUCP (David W. Berry)
Newsgroups: comp.sys.mac
Subject: Re: Can Sell old SIMMS to II owner?
Message-ID: <1508@apple.UUCP>
Date: Wed, 19-Aug-87 17:46:22 EDT
Article-I.D.: apple.1508
Posted: Wed Aug 19 17:46:22 1987
Date-Received: Sat, 22-Aug-87 05:00:40 EDT
References: <334@ge-mc3i.UUCP> <3681@cit-vax.Caltech.Edu>
Reply-To: dwb@apple.UUCP (David W. Berry)
Distribution: world
Organization: Apple Computer Inc., Cupertino, USA
Lines: 27
Keywords: SIMMS, 256k, MacII

In article <3681@cit-vax.Caltech.Edu> wetter@tybalt.caltech.edu.UUCP (Pierce T. Wetter) writes:
>In article <334@ge-mc3i.UUCP> sterritt@ge-mc3i.UUCP (Chris Sterritt) writes:
>>Hello,
>>	I just got an upgrade to 2.5 Megs from Dove (which I adore), and
>>a friend of mine just got a Mac II, with only a Meg.  My question is, can
>>I sell him the two 256K simms (since they'll at least fit in his machine)
>>to upgrade him to 1.5 megs?  
>>	Has anyone *done* this, or *know* of a reason why it won't work?
>
>   HA! Another victim! No you cannot upgrade the Mac II to 1.5 Meg. The Mac 
>II only allows memory sizes of 1,2,5,8 etc. I know this because some people
>here bought some upgrade kits to give themselves 3 meg. Now they are all 
>upgrading to 5 meg. 
	Far from being a fluke or plot to sell more memory on Apple's 
	part the reason the memory upgrades come in 1,2,5,8 combinations
	is that the 68020 has 32-bit wide memory.  Thus memory must
	be added in 32-bit wide increments.  This means you have to
	add or replace 4 simms (since each one is 8-bits wide) at a
	time.
	
	It's similar to why the Mac {plus,se} can only be upgraded to
	.5, 1, 2.5 or 4 meg.  The 68000 utilizes 16-bit wide memory
	and thus must be upgraded 2 simms at a time.
-- 
	David W. Berry
	dwb@well.uucp                   dwb@Delphi
	dwb@apple.com                   293-0752@408.MaBell