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From: oster@dewey.soe.berkeley.edu (David Phillip Oster)
Newsgroups: comp.sys.mac.programmer
Subject: Re: screen swapping
Message-ID: <23563@ucbvax.BERKELEY.EDU>
Date: 9 Apr 88 21:27:21 GMT
References: <gWL7U8y00UjIzJY07P@andrew.cmu.edu>
Sender: usenet@ucbvax.BERKELEY.EDU
Reply-To: oster@dewey.soe.berkeley.edu.UUCP (David Phillip Oster)
Organization: School of Education, UC-Berkeley
Lines: 11

don't do it. In machines that have a second video page, it resides at a
fixed offset below the primary page, which is at
screenBits.bounds.baseAddr. Note: 

1.) finding the alternate page will be different on a Mac II.
2.) not all mac IIs have video adapters that support the second screen
buffer.
3.) almost all non-mac IIs have something, an INIT, a ram cache, or
something, that is already using the alternate video pages memory.

Just allocate a simple offscreen buffer, and copybits it onto the screen.