Well...
It turns out the error was in the sample I've used, where you will see the
following lines after VBLANK:
LDA #0 (instead of LDY!)
STY PF0
STY PF1
STY PF1
STY GRP0
STY GRP1
STY ENAM0
STY ENAM1
STY ENABL
so.. the black lines were sprites :)
Will think better next time :)
thanks!
Rasty.-
----- Original Message -----
From: "Thomas Jentzsch" <tjentzsch@xxxxxx>
To: <stella@xxxxxxxxxxx>
Sent: Sunday, June 09, 2002 13:00
Subject: Re: [stella] Hello, and.. my game
> At 09.06.2002, 13:10, Fabrizio Zavagli wrote:
> > About the asymmetrical playfields, there's something I don't really
> > understand about it.
> > I was modifying the above-mentioned sample to squeeze and slightly
optimize
> > it and decided to use the Y register instead of memory.
> > When I've implemented Y, I started having some garbage (black vertical
> > lines) on the screen when re-writing to PF0...
>
> > snip
>
> > As you see, I've just replaced ScanPix with the unused Y register...
that
> > should take less cycles and memory.. but I get that weird artifact!
>
> > Actually I get the artifact whenever I write to the Y register..
>
> If you don't find a bug inside the code, you should check the timings.
> Probably a hidden page-crossing cycle is causing that problem.
>
> Where exactly are the artefacts? And how do they look like. The best
> would be to post the code and/or a binary.
>
> Have fun!
> Thomas
> _______________________________________________________
> Thomas Jentzsch | *** Every bit is sacred ! ***
> tjentzsch at web dot de |
>
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