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From: hodas@eniac.seas.upenn.edu (Josh Hodas)
Newsgroups: comp.sys.mac
Subject: Re: New SIMMs for the Macintosh IIci???
Message-ID: <14730@netnews.upenn.edu>
Date: 26 Sep 89 03:27:32 GMT
References: <1150@orbit.UUCP>
Sender: news@netnews.upenn.edu
Reply-To: hodas@eniac.seas.upenn.edu.UUCP (Josh Hodas)
Organization: University of Pennsylvania
Lines: 44

In article <1150@orbit.UUCP> granteri@pnet51.orb.mn.org (Grant Erickson) writes
>jeff@ndcheg.cheg.nd.edu (Jeffrey C. Kantor) writes:
>>In art <1149@orbit.UUCP>, granteri@pnet51.orb.mn.org (Grant Erickson) writes:

>>> ... I was enlightend to the fact that in
>>> the IIci you must use 80 nanosecond F)ull P)age M)ode SIMMs. These must be
>>> used to take advantage of the burst-mode of the 68030. 
>>>  [stuff deleted]
>>
>>What is a F)ull P)age M)ode SIMM?  I know what the 80ns bit is all about,
>>but what does the FPM bit mean?
>>More to the point, if I order 80ns SIMMs from the usual list of SIMM vendors,
>>will they work in a MacIIci?

>Well as Paul Pashibin of Apple Corporate in Bloomington, MN explained it as
>being this. Lets say you have a data word. The 68030 grabs the first 1/4 in 5
>cycles, the 2nd 1/4 in 5 cycles, the 3rd 1/4 in 5 cycles, and the final 1/4 in
>5 cycles. This ends up taking 20 cycles consequently. So with the FPM SIMMs
>together with the 68030's burst mode, it reads 1st: 5 Cycles and the next
>consecutive 3 in 2 Cycles each. There for you have a total of 11 Cycles
>compared to 20 giving you a 181% speed increase in that situation. I myslef do
>not know if people like Chip Merchant will have these at the current low $89
>price for NORMAL 80Ns SIMMs.
>
>Grant Erickson

Well, I called Chip Merchant this afternoon and the woman on the phone claimed 
that their Samsung 80ns SIMMS are FPM.  I do not know how one could confirm 
this though.  If I post a chip # from the simm, does someone have a Samsung
part list to look it up on.  Speed was always an easy thing to identify from
the -xx number, but I have no idea what identifies an FPM chip.

Josh



-------------------------

Josh Hodas    (hodas@eniac.seas.upenn.edu)
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