Newsgroups: comp.sys.mac.system
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!yale.edu!cmcl2!mcclb0.med.nyu.edu!huff
From: huff@mcclb0.med.nyu.edu (Edward J. Huff)
Subject: Re: MaxAppleZoom theory
Message-ID: <1991Jun26.071059.1@mcclb0.med.nyu.edu>
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Organization: NYU Chemistry, 31 Washington Place, NY, NY 10003
References: <D2150025.izydhe@brain.UUCP> <7723@emory.mathcs.emory.edu>
Date: 26 Jun 91 07:10:59 EDT
Lines: 24

In article <7723@emory.mathcs.emory.edu>, ospwd@mathcs.emory.edu (Peter Day {EUCC}) writes:
>> From: chuck@brain.UUCP (Chuck Shotton)
> 
>> A) What makes you think there is ANYTHING stored in "RAM" on a video
>> card after the power is shut off? (IS it? Do you know if Toby cards
>> have NV RAM?)
> 
> How can removing the video card and putting it back in make a
> difference? Also, after the card is replaced, the display reverts to
> black and white and must be reset to color. Clearly some stored
> information got lost. Perhaps NV RAM in the Mac related to the display
> gets cleared, and that's where the date is stored.
> 

Page 127 of Designing Cards and Drivers for the Macintosh Family,
Second Edition, states "There are six bytes reserved in the parameter RAM
(PRAM) of a Macintosh II-family computer for each slot. ... Initialization
occurs when the Macintosh Operating System detects a card for the first time
or when the Slot Manager finds a BoardId in a Board sResource that is
different from the BoardId in the corresponding sPRAMInit record."

It sounds like the software is using the PRAM bytes.  Not very nice, since
that space is supposed to be used by the card's driver software.

