Path: utzoo!utgpu!watmath!clyde!att!rutgers!apple!bionet!agate!saturn!ucscb.UCSC.EDU!lechner
From: lechner@ucscb.UCSC.EDU (Eric Lechner)
Newsgroups: comp.sys.cbm
Subject: C64 text screen
Summary: wanted: method to swap text screens in memory
Keywords: text xcreen page swapping
Message-ID: <5673@saturn.ucsc.edu>
Date: 8 Dec 88 09:35:55 GMT
Sender: usenet@saturn.ucsc.edu
Reply-To: lechner@ucscb.UCSC.EDU (Eric Lechner)
Organization: University of California, Santa Cruz; CATS
Lines: 19


I am writing an assembly language "life" program and would like to do this:
It needs to alternate between two screens, without copying the screen (due to
time considerations. I am trying to optimize running time).
I would like to keep each screen in a different place in memory, so
that I need only change the pointer to the text screen.

I have tried the 128 programmer's reference guide, and have tried
altering location 648 (a page pointer to the top of the text screen) but
the display does not change when I change that pointer.

What am I doing wrong?  Is there a pointer in the video chip that I need to
alter as well as the other pointer?  Am I overlooking anything else, as well?

Any help will be appreciated.
		Eric
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	     Eric Lechner 115 Seton Way   Santa Cruz, CA  95060
            lechner@ucscb.ucsc.edu   ...ucbvax!ucscc!ucscb!lechner