Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!uunet!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga.tech
Subject: Re: 100ns SC ZIPs fast enough for A3000-25?
Keywords: DRAM 100ns
Message-ID: <14199@cbmvax.commodore.com>
Date: 4 Sep 90 23:24:02 GMT
References: <1990Aug30.230504.19264@jarvis.csri.toronto.edu>
Reply-To: daveh@cbmvax (Dave Haynie)
Distribution: comp
Organization: Commodore, West Chester, PA
Lines: 24

In article <1990Aug30.230504.19264@jarvis.csri.toronto.edu> leblanc@eecg.toronto.edu (Marcel LeBlanc) writes:

>The subject line says it all!  Are 100ns static column DRAMs (ZIPs) fast
>enough for best-memory-speed operation on an Amiga 3000?  I thought Dave
>Haynie had stated that 100ns SC DRAMs are all that are needed for the
>A3000-25, but every post about SC ZIPs seems to be talking about the price of
>80ns chips.

OK.  The deal is, the RAMSEY chip was designed to use 100ns DRAMs, for 16MHz
or 25MHz (the chip is optimized for either; it runs basic 4 clock cycles for
16MHz, 5 clock cycles for 25MHz).  However, the IC people aren't able to
guarantee operation with 100ns DRAMs over the full power and temperature
range of the chip, so we call for 80ns DRAMs.  I can tell you that 100ns 
parts would work in most of the systems most of the time, but unless I can
say they work in all of the systems all of the time, I don't recommend it
(nor does Greg Berlin, who designed RAMSEY and wrote the specs, which is what
the 80ns figure from the A3000 manual is based on).

>Marcel A. LeBlanc  --  Electrical Engg Computer Group, Univ. of Toronto

-- 
Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: hazy     BIX: hazy
      Get that coffee outta my face, put a Margarita in its place!