[stella] Asymmetric Playfield

Subject: [stella] Asymmetric Playfield
From: Andrew Towers <mariofrog@xxxxxxxxxxx>
Date: Tue, 04 Mar 2003 14:19:12 +1100

I am still yet a beginer at this programing I figured out how to do
asymetical playfields with a small bug in it though.

In the "How to Draw an Asymmetric Reflected Playfield" example on The Dig (http://www.neonghost.com/the-dig/docs.html), there is a timing error in the comments. In the display kernel is the following code:

        ;PF2 rewrite must begin at exactly cycle 45!!, no more, no less
        STA PF2                 ;[45]+2 = *47*  ; > 46 PF2 no longer visible

Whereas the actual timing of STA PF2 is 3 cycles, and the comment
should read something like:

        ;PF2 rewrite must begin at exactly cycle 45!!, no more, no less
        STA PF2                 ;[45]+3 = *48*  ; > 47 PF2 reflected visible

Just thought I'd mention this in case you're relying on cycle 47 access
to do the changeover. If you add up the cycles in the kernel, it comes
out at cycle 48.

- M.

ps. the links to Eckhard's pages on The Dig are giving 404 errors :(


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