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From: olson@endor.harvard.edu (Eric Olson)
Newsgroups: comp.sys.mac
Subject: Re: Video memory on Mac II
Message-ID: <2819@husc6.UUCP>
Date: Thu, 10-Sep-87 11:11:46 EDT
Article-I.D.: husc6.2819
Posted: Thu Sep 10 11:11:46 1987
Date-Received: Sat, 12-Sep-87 07:46:59 EDT
References: <162@osupyr.UUCP>
Sender: news@husc6.UUCP
Reply-To: olson@endor.UUCP (Eric Olson)
Organization: Aiken Computation Lab Harvard, Cambridge, MA
Lines: 29
Keywords: memory ram mac video

In article <162@osupyr.UUCP> czei@osupyr.UUCP (Michael S Czeiszperger) writes:
>This probably was discussed previously, but here it goes:
>I'm trying to figure out the effects of adding a 24 bit
>buffer card to our mac II. Is the memory needed for video 
>taken from regular virtual memory, or is it contained

Picky point:  No virtual memory on the Mac II (Yet).

>on the card?   Since a full screen image at 24 bits would
>probably fill up about 2.25 meg, the addition of the
>higher resolution board would contain the hidden costs of
>higher memory requirements.   

A 24-bit card does not use any more main memory per se, however, applications
that build off-screen PixMaps (images) that match the current maximum
screen depth would consume more memory (assuming the card is actually set
to run in 24-bit mode).  The actual screen memory is on the card, and
not available to anything but the video card.

The only people I know of that are even planning 24-bit video is SuperMac
(makers of the pretty, big, SuperMac 8-bit color display for the Mac II).
I think they're going to do it by using 3 of their 8-bit cards.

-Eric




Eric K. Olson		olson@endor.harvard.edu		harvard!endor!olson