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From: captkidd@athena.mit.edu (Ivan Cavero Belaunde)
Newsgroups: comp.sys.mac
Subject: Re: Upgrade Memory on SE/030
Keywords: IIci, RAM, SIMMs
Message-ID: <14877@bloom-beacon.MIT.EDU>
Date: 4 Oct 89 17:19:22 GMT
References: <12679@orstcs.CS.ORST.EDU> <35202@apple.Apple.COM> <1989Oct3.144854.24428@agate.berkeley.edu> <35221@apple.Apple.COM>
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: captkidd@athena.mit.edu (Ivan Cavero Belaunde)
Organization: Massachusetts Institute of Technology
Lines: 30

In article <35221@apple.Apple.COM> dwells@Apple.COM (Dave Wells) writes:
>Yes, it's true.  The Macintosh IIci is the first to allow the RAM in bank B
>to be of higher density than the RAM in bank A.  In fact, you can install RAM
>in bank B and take the SIMMs out of bank A and the Macintosh will work fine.
>(Minus built-in video, which uses RAM from bank A.)
>
>This fantastic new functionality :-) is enabled by the new Memory Decode Unit
>chip that replaces the old GluChip from previous Macintosh II models.

Correct me if I'm wrong, but I was under the impression that the reason this
is an important feature is that cycle-stealing for the built-in video slows
down access to memory in bank A.  The ability to have higher density memory
in bank B rather than bank A should then result on a lesser performance
degradation when using built-in video.  If you have 5MB of RAM, and you put
4MB on bank A and 1 on bank B (the only possible configuration before),
the 4MB will be "slower memory" than the 1MB.  Thus it is useful and
desirable to put higher density RAM in bank B when using built-in video.

>-Dave

-Ivanski

	"I'm going to kill everyone in this room"

		"Now that's darn rude."

	-The Joker and David Endochrine, _Batman: The Dark Knight Returns_
		by Frank Miller

Internet: captkidd@athena.mit.edu