At 6:21 PM -0800 11/16/99, Bill Studenmund wrote:
>On Tue, 16 Nov 1999, Henry B. Hotz wrote:
>
>>  Since I was the "private email" source Wonko referred to this is not
>>  independent confirmation, but I'm pretty sure of myself on these points.
>>
>>  >I'm pretty sure only the II required PALs; the IIx motherboard was designed
>>  >to accept standard 4MB SIMMs.
>>
>>  I do not know of anyone trying larger than 4MB SIMMs in an original II.
>>  The point about 4Mb chips being the problem even if it was a 1MB SIMM was
>>  well made.  The problem is that there was a test mode invented for the 4Mb
>>  chips which the original II motherboard design did not know it needed to
>>  avoid;  hence random crashes.  My IIcx does not have the problem, and the
>>  IIx and SE/30 were all similar vintage.
>
>I agree that the cx doesn't have the problem, but according to
>http://www3.simpletech.com/cgi-bin/configurator.cgi , the II and IIx use
>the same memory.
>
>I've never understood why the IIx had the problem when the IIcx didn't - I
>_thought_ they were released at the same time.

According to the Apple Memory Guide 
<http://til.info.apple.com/techinfo.nsf/artnum/n20025>, the Mac IIx 
requires PAL type SIMMs in densities higher than 1 MB.  The same 
reference has no mention of PAL type SIMMs on the page for the IIcx.

Apple's AppleSpec database 
<http://www.info.apple.com/applespec/applespec.taf> says that the IIx 
was introduced 9-19-88 (discontinued 10-15-90), and the IIcx was 
introduced 3-7-89 (discontinued 3-11-91).  The IIcx's time as a 
product was about a half year behind the IIx's.

It seems that Apple fixed the problem by the time the IIcx was 
released, but either didn't bother to fix the problem on the later 
IIx models, or didn't want to explain how to tell the difference in 
the Apple Memory Guide.




Eric Damien Berna
eric@thiel.com

NetBSD 1.3.3 on a Mac Quadra 800
NetBSD-current on a Power Mac 8500