Re: [stella] Linux makewav 4.1 text file

Subject: Re: [stella] Linux makewav 4.1 text file
From: "Eckhard Stolberg" <Eckhard_Stolberg@xxxxxx>
Date: Sun, 19 Aug 2001 22:27:22 +0200
> I'm a brand-new list subscriber, it's good to meet you all.

Welcome to the wonderfull world of classic console programming. ;-)

> I am having a minor problem with player vertical positioning... not
> sure if I can explain it properly... when I position the players in
> the first 30-40 pixels of the display, they appear to be shifted down
> one scanline (my kernel is 2 scanlines per iteration, low res)... I
> will post the code as soon as I clean out the huge sections of
> commented out code and the profanity (cussing at the thing doesn't
> really help, but I keep doing it anyway...)

Then you'll now discover one of the key points in VCS programming:
cycle counting. Your code to display the player probably takes longer
than the VCS needs to get to the 40th pixel in the scanline. When your
change to the graphics register happens, the VCS is already past that
point, so that the change will only take effect in the next scanline.
You'll have to restructure your code in such a way that the write
access to the graphics register will happen during the horizontal
blank period.

> The other thing is, I'm using ca65 (from for a cross
> assembler... from reading the archives, it appears that dasm is the
> standard here. Should I take the time to port my code to dasm before
> posting it here? Shouldn't take long (minor syntax differences can
> probably be fixed by a perl script), but I wondered if anyone else
> is using ca65? I chose it more or less randomly (well, already had it
> installed, as it's a part of the cc65 cross compiler).

Of course you can use the assembler that you like best. However,
since most of us are most familar with DASM sysntax, you'll probably
get more responses to your questions, if you post your code in that
format too. And since you probably haven't build up a large code base
in ca65 yet, and since you also haven't chosen ca65 for any special
reason, it might still be possible to switch assemblers without too
many problems.

Ciao, Eckhard Stolberg

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