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From: ephraim@wang7.UUCP (ephraim)
Newsgroups: comp.sys.mac
Subject: Re: Can Sell old SIMMS to II owner?
Message-ID: <135@wang7.UUCP>
Date: Wed, 19-Aug-87 08:43:52 EDT
Article-I.D.: wang7.135
Posted: Wed Aug 19 08:43:52 1987
Date-Received: Sat, 22-Aug-87 07:31:40 EDT
References: <334@ge-mc3i.UUCP>
Organization: Wang Laboratories, Lowell, MA, USA
Lines: 22
Keywords: SIMMS, 256k, MacII
Summary: 6 SIMMs is not a choice

In article <334@ge-mc3i.UUCP>, sterritt@ge-mc3i.UUCP (Chris Sterritt) writes:
> 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?

According to anything I've seen about upgrading the II's memory,
the supported memory sizes are 1, 2, 4, 5, and 8 megabytes.  The
reason is that SIMMs are 8 bits wide and the Mac II data path is
32 bits wide.  So, SIMMs must be installed in groups of four.
You can have 4 256K SIMMs (1 Meg), 8 256K SIMMs (2 Meg), 4 1M SIMMs
(4 Meg), 4 1M + 4 256K (5 Meg), or 8 1M (8 Meg).
 
You can't have 6 256K SIMMs (1.5 Meg).  In fact, you can't have any
combination totalling 1, 2, 3, 5, 6, or 7 SIMMs, nor can you have any
mixture except 4 and 4.



-- 
Ephraim Vishniac
masscomp!wang7!ephraim