Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!apple!uokmax!rob
From: rob@uokmax.ecn.uoknor.edu (Robert K Shull)
Newsgroups: comp.sys.mac.hardware
Subject: Re: MacII Memory Limits Again
Message-ID: <1989Nov26.141532.2099@uokmax.ecn.uoknor.edu>
Date: 26 Nov 89 14:15:32 GMT
References: <0ZPrKQq00WB48UuFcB@andrew.cmu.edu>
Reply-To: rob@uokmax.UUCP (Robert K Shull)
Organization: University of Oklahoma, Engineering Computer Network, Norman, OK
Lines: 31

In article <0ZPrKQq00WB48UuFcB@andrew.cmu.edu> ag14+@andrew.cmu.edu (Albert H. Gough) writes:
>get 4 Mb SIMMs made of 1 Mb chips they will not work because the
>MacII ROM "will not recognize 4 Mb SIMMs".  It seems to me this is
>a ROM bug that has nothing to do with the new chip design.

Perhaps Apple could offer the ROM/SWIM upgrade without requiring purchase of
the SuperDrive? This might make people a LITTLE happier (not much, read below)..

BTW, summary of TN176:
	4 meg SIMMs, produced from either 1 mbit or 4 mbit DRAMs, won't work
in a Macintosh II due to an unspecified problem in the ROM startup code.
	4 meg SIMMs, produced from 1 mbit DRAMs, should work in a IIx or a
ROM-upgraded II.
	4 meg SIMMs, produced from 4 mbit DRAMs, will NOT work in a IIx OR
a ROM-upgraded II. This is due to the addition of an unanticipated extra
test mode and addition of new meaning to a particular control line on the DRAMs.
	4 meg SIMMs, produced from either 1 mbit or 4 mbit DRAMs, should work
on SE/30, IIcx, and IIci.

	The note also says that modification of the SIMM (by adding an IC to
insure the new mode doesn't get triggered) should allow IIx or ROM-upgraded IIs
to work with 4 meg SIMMs using the 4 mbit DRAM.
	Unfortunately, this is bound to mean $$ (my opinion) if only the
Mac II and IIx need this special SIMM.
	The note concludes by saying that there are no plans to recall,
upgrade, OR change the design of the machines which exhibit this problem.
Apparently the currently-being-produced IIx's still have the problem.
	Robert
-- 
Robert K. Shull
rob@uokmax.ecn.uoknor.edu				chinet!uokmax!rob