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Groups > comp.sys.apple2.programmer > #2214

Re: Accessing auxiliary memory for double lo-res graphics

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On Sunday, February 7, 2016 at 3:37:56 PM UTC-6, AppleIIGSMarc wrote:
> > Note that this only supports text and double lo-res page 1. There is no
> > special bank switch mechanism for page 2, so another method would be
> > needed to access the auxiliary buffer if you want to do things like page
> > flipping double lo-res.
> 
> Do you (or anyone else reading this) have any advice on how to write to lo-res page 2 in the auxiliary buffer?  I've been working on a lo-res game that uses sprites and page flipping, and I'd like to rewrite it to use double lo-res graphics for the increased horizontal resolution.  Being able to page flip would help a lot to update the graphics cleanly and reduce flicker.  Is there an area of memory I can place my code and data that won't be affected by the RDAUX/WRAUX switches, such as above $BFFF?  What about using the alternate banks at $D000-$DFFF?  At the moment, my game is running under DOS 3.3 if that helps.
> 
> I'll continue trying to read up on the memory layout of the II and the softswitches that control it, but if anyone has any suggestions that could point me in the right direction... :)
> 
> -Marc


First off, it is not necessary to page flip when using double lo-res graphics since the grid is so small, 80x48, which is a lot smaller than dbl hi-res which has 560 pixels x 192 lines.

Animation in Dbl-hi-res is achieved by pre-shifted shapes which can work for dbl-lo-res as well.

And second, you cannot view screen #2 and draw on screen #1 due to the way the softswitches work.  You will need the softswitches set in a certain order just to view screen #2, but those same softswitches are used in drawing to the Auxiliary memory of screen #1, so screen #2 will get switched out.

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Accessing auxiliary memory for double lo-res graphics AppleIIGSMarc <appleiigsmarc@gmail.com> - 2016-02-04 17:50 -0800
  Re: Accessing auxiliary memory for double lo-res graphics dempson@actrix.gen.nz (David Empson) - 2016-02-05 16:59 +1300
    Re: Accessing auxiliary memory for double lo-res graphics AppleIIGSMarc <appleiigsmarc@gmail.com> - 2016-02-04 21:44 -0800
    Re: Accessing auxiliary memory for double lo-res graphics AppleIIGSMarc <appleiigsmarc@gmail.com> - 2016-02-07 13:37 -0800
      Re: Accessing auxiliary memory for double lo-res graphics dempson@actrix.gen.nz (David Empson) - 2016-02-08 13:42 +1300
        Re: Accessing auxiliary memory for double lo-res graphics AppleIIGSMarc <appleiigsmarc@gmail.com> - 2016-02-08 15:54 -0800
      Re: Accessing auxiliary memory for double lo-res graphics gids.rs@sasktel.net - 2016-02-08 14:30 -0800
        Re: Accessing auxiliary memory for double lo-res graphics AppleIIGSMarc <appleiigsmarc@gmail.com> - 2016-02-08 18:13 -0800
          Re: Accessing auxiliary memory for double lo-res graphics Mark Lemmert <mark.lemmert@gmail.com> - 2016-02-13 14:08 -0800
          Re: Accessing auxiliary memory for double lo-res graphics Mark Lemmert <mark.lemmert@gmail.com> - 2016-02-13 14:12 -0800
            Re: Accessing auxiliary memory for double lo-res graphics AppleIIGSMarc <appleiigsmarc@gmail.com> - 2016-02-15 14:51 -0800
          Re: Accessing auxiliary memory for double lo-res graphics gids.rs@sasktel.net - 2016-02-14 14:40 -0800
            Re: Accessing auxiliary memory for double lo-res graphics gids.rs@sasktel.net - 2016-02-14 15:05 -0800
            Re: Accessing auxiliary memory for double lo-res graphics gids.rs@sasktel.net - 2016-02-14 15:52 -0800
              Re: Accessing auxiliary memory for double lo-res graphics AppleIIGSMarc <appleiigsmarc@gmail.com> - 2016-02-15 15:14 -0800
        Re: Accessing auxiliary memory for double lo-res graphics BLuRry <brendan.robert@gmail.com> - 2016-02-24 22:07 -0800
          Re: Accessing auxiliary memory for double lo-res graphics qkumba <peter.ferrie@gmail.com> - 2016-02-25 08:22 -0800

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