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From: stew@endor.UUCP
Newsgroups: comp.sys.mac
Subject: Re: SIMMS in Mac II
Message-ID: <2364@husc6.UUCP>
Date: Sat, 20-Jun-87 21:58:18 EDT
Article-I.D.: husc6.2364
Posted: Sat Jun 20 21:58:18 1987
Date-Received: Sun, 21-Jun-87 12:00:43 EDT
References: <1065@apple.UUCP> <1067@apple.UUCP> <2897@zen.berkeley.edu> <1838@ames.UUCP>
Sender: news@husc6.UUCP
Reply-To: stew@endor.UUCP (Stew Rubenstein)
Organization: Aiken Computation Lab Harvard, Cambridge, MA
Lines: 33
Keywords: SIMMS, Mac+, MacII

In article <1838@ames.UUCP> woo@pioneer.UUCP (Alex Woo) writes:
>Is there any convenient way to add memory to a Mac II except for
>adding SIMMS?  How about 1MB chip SIMMS?
>
>I would much rather buy a NuBus Board with extra sockets that I could
>fill later with inexpensive chips.  Any such products available?
>
>Alex

1MB SIMMs will work fine, they are just rather expensive.  From Apple,
they list at $1000 per pair, and you must buy an even number of pairs
(two to give you 5 Mb total, four to give you 8Mb plus one useless set
of 256Mb SIMMs).  If you have a plus or SE which happens to have 120ns
chips (some do, some don't, and this doesn't seem to correlate with age),
then you can buy one set of 1Mb SIMMs for $1000 (or whatever), put them
into your SE or Plus, and take all four 256KB SIMMs out and put them in
your Mac II.  That'll give you 2Mb in each machine.  That's in fact what
I have done.

NuBus boards are limited to 1Mbyte each, at present, due to the
limited way in which the bus is mapped for compatibility with the 24
bit Mac OS and fake MMU.  This breaks down into 1MByte mapped to each
slot, 8MB to motherboard memory, 1MByte mapped to ROM, and 1MByte for
the I/O devices on the motherboard, for a total of 16Mb or 2^24 bytes.

There's also the problem that the NuBus space is not contiguous with
the motherboard RAM, I don't think the system would automatically be
able to use it.  Your application would have to know about it somehow
and use it itself.
Stew Rubenstein
Cambridge Scientific Computing, Inc.
UUCPnet:    seismo!harvard!rubenstein            CompuServe: 76525,421
Internet:   rubenstein@harvard.harvard.edu       MCIMail:    CSC