Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uwm.edu!rpi!nyser!rodan!jstewart
From: jstewart@rodan.acs.syr.edu (Ace Stewart [Jonathan III])
Newsgroups: comp.sys.mac
Subject: Re: Mac IIci SIMMs
Keywords: fast page mode - what is this?
Message-ID: <954@rodan.acs.syr.edu>
Date: 6 Oct 89 17:05:48 GMT
References: <10730@phoenix.Princeton.EDU>
Reply-To: jstewart@rodan.acs.syr.edu (Ace Stewart [Jonathan III])
Organization: Syracuse Univ/Eastman Kodak Co.
Lines: 34

In article <10730@phoenix.Princeton.EDU> jklee@phoenix.Princeton.EDU (James Kin Wah Lee) writes:

>What are "fast page mode" SIMMs and how are they different from
>"normal" SIMMs?  Is one obligated to use only these special SIMMs
>in the IIci?  More importantly, can one
>obtain these from the vendors who advertise in MacWeek for
>the same prices as "normal" SIMMs???


	Hokay, having recently (ie this morning) talked with a
Systems Engineer from Apple, here is the scope as seen through my
eyes from his words. The 80ns are rather unique. They can be
standard memory chips in that they run 80ns, but there is a difference
in how they perform in connection to the CPU. The IIci has what is
called page-burst mode. It can take multiple commands per cycle,
and this is what is unusual. The fact that this occurs allows for
nothing to do with the SIMMS itself, so therefore they are standard
80ns chips.

However, Apple is offering an extended SIMMS chip that has a parity
check sequencer on it. For those of you familiar with parity, you
will realize that a parity error occurs rather infrequently, and
the S.E. I spoke with was quoted as saying on the average of 7 years.
This is a chip that must be bought directly through Apple itself, and
has its' biggest sales through government institutions. Not something
the normal person would need....


		Does this help at all?   Ace
-- 
| Ace Stewart (Jonathan III)                             |A       /\       |
| Affiliation: Eastman Kodak Company. Rochester New York |      _/  \_     |
| Internet/ARPA: jstewart@rodan.acs.syr.edu              |      \_  _/     |
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