Path: utzoo!attcan!uunet!ccicpg!felix!dhw68k!thecloud
From: thecloud@dhw68k.cts.com (Ken McLeod)
Newsgroups: comp.sys.mac
Subject: Re: System 6.0.2 seems to work on a 2 meg 512Ke
Message-ID: <15071@dhw68k.cts.com>
Date: 12 Nov 88 08:52:07 GMT
References: <4825@polyslo.CalPoly.EDU> <20031@apple.Apple.COM> <68258@felix.UUCP> <5630@polyslo.CalPoly.EDU>
Reply-To: thecloud@dhw68k.cts.com (Ken McLeod)
Organization: Wolfskill residence; Anaheim, CA (USA)
Lines: 41

In article <5630@polyslo.CalPoly.EDU> dorourke@polyslo.CalPoly.EDU (David M. O'Rourke) writes:
>In article <68258@felix.UUCP> kehr@felix.UUCP (Shirley Kehr) writes:
>>
>> {Talks about how map & sound don't work on a 512Ke with sys 6.0.2
>
>  Both map & the sound CDEV need the newer clock chip in the Macintosh Plus
>and beyond to work.  The new verions of the CDEV's check to make sure that
>the clock chip is present before they will even consider working.  If they
>don't find the new clock chip then they don't show up in the control
>panel.

  There seems to have been a lot of confusion about the extra bytes in
the "new" clock chip, and what they are used for. I believe that the Sound
cdev stores the currently selected beep sound in this extra area, and the
Map cdev stores the Current Location there, too. The Nov. issue of MacUser
(my subscription hasn't expired, yet) claims that "applications such as
travel-information programs and HyperCard can use this information directly,
just as they can use the time settings."

  There are two UNDOCUMENTED traps, _ReadXPRAM and _WriteXPRAM, which
handle reading and writing to the extended PRAM area. At least, they
aren't documented in any TechNotes through 210...

  Now for my question: (two parts): how can I determine the total size
of PRAM, and how can I make use of _ReadXPRAM to access the "new"
settings? The old PRAM was 20 bytes (or at least, the data structure
it held was that size), but how to tell the "new" size?? I'd like to
be able to incorporate this in the next version of MacEnvy, so that
users can determine whether or not they have the Plus clock chip in a
512/512E machine. (Apparently, the new clock chip was used in 512K Macs
months before the introduction of the Plus...)

  Thanks in abundance...
 -ken


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Ken McLeod     :.     .:    uucp: {spsd, zardoz, felix}!dhw68k!thecloud
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