Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!pasteur!ucbvax!ucdavis!deneb.ucdavis.edu!ecs175f037
From: ecs175f037@deneb.ucdavis.edu (Greg DeMichillie)
Newsgroups: comp.sys.mac
Subject: Re: 1.75Mb Mac Plus possible?
Summary: No, you must but SIMMS in two at a time
Message-ID: <3366@ucdavis.ucdavis.edu>
Date: 8 Dec 88 21:10:46 GMT
References: <870265@hpcilzb.HP.COM>
Sender: uucp@ucdavis.ucdavis.edu
Reply-To: lgdemichillie@ucdavis.edu (Greg DeMichillie)
Organization: University of California, Davis
Lines: 34

In article <870265@hpcilzb.HP.COM> cnc@hpcilzb.HP.COM (Chris Christensen) writes:
>
>I have always heard about making a 2.5Mb Mac+ or a 4Mb one.
>Can you replace one of the SIMMs to get a 1.75Mb machine or three to get a
>3.25Mb one? Or is there something magical about replacing an even number of
>them? It sure would be nice on my pocket book if I could upgrade one SIMM
>at a time.
>
>Chris Christensen

Sorry, but when adding SIMMS to a Mac Plus or SE you must add them in pairs.
That means that these are the possible combinations:

		      Bank A           Bank B
                   256K    256K     256K    256K     = 1MB
		   256K    256K      1MB     1MB     = 2.5MB
		    1MB     1MB      1MB     1MB     = 4 MB

It is technically possible to have this also:

		  empty   empty      1MB     1MB     = 2MB

although that would mean throwing away the .5MB that was already in you
Mac.  This is how Apple makes the Mac SE 2/40.

You can use third party memory expansion kits that piggy-back another
pair of 256K SIMMS onto the existing 256K ones.  That would give you a
total of 2MB but that is not Apple supported or recommended.  And you'd
have to throw them away to go to 4MB later on anyway.

-----
Greg DeMichillie  Apple Student Rep - UC Davis 
lgdemichillie@ucdavis.edu     ucbvax!ucdavis!lgdemichillie      AppleLink:ST0178
Disclaimer: If you've seen one disclaimer, you've seen them all.