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From: ks26+@andrew.cmu.edu (Kenneth Sykes)
Newsgroups: comp.sys.ibm.pc
Subject: Re: PS/2 VGA Video Pages
Message-ID: <cVVtZOy00V41zEo09l@andrew.cmu.edu>
Date: Thu, 29-Oct-87 14:39:06 EST
Article-I.D.: andrew.cVVtZOy00V41zEo09l
Posted: Thu Oct 29 14:39:06 1987
Date-Received: Wed, 4-Nov-87 02:00:29 EST
Organization: Carnegie Mellon University
Lines: 10
In-Reply-To: <45900086@uxe.cso.uiuc.edu>


While VGA mode 12h (640x480x16) does not support page switching,
there is more than 480 lines worth of screen memory.  The 640x480 buffer
uses 80x480 bytes of memory (approx. 38000 bytes).  The remaining 26000
bytes or so in the 64K segment is valid screen memory.  I've used this to
save and restore screens quickly (along with write mode 1).  The one caveat
I've
found so far is the Microsoft mouse seems to trash/use the memory immediately
below scan line 480, so I use the memory starting at scan line 500, which
seems
to work.   Fine.