Re: [stella] Video Chess player usage

[Glenn Saunders <cybpunks@xxxxxxxxxxxxx>]

I took a screenshot of Video Chess and overlayed a diagram based on my
understanding of the kernel.

Please take a look at it and let me know if it's accurate.

I wasn't aware of the ball trick.  I can understand using it if you don't
have enough time to rewrite the playfield register for a nonsymmetrical
playfield.  But aren't there alternatives?  Wouldn't it work if playfield
were set to repeat and the entire board were shifted over to the right (or
left) by one playfield pixel?  Would that throw the sprite timings off?
Maybe Bob wanted to make sure the board was in the exact center.

BTW, I now have a script in the image processing program that I'm using
(Aura) that can simulate the 2600 drawing each scanline line by line.  So I
plan on using that in addition to overlayed diagrams like the attached to
accompany the voice kernel explanation.

Ideally I'd want to also have the source code listing appear changing in
time with the scanline, but I haven't figured out how to do that.

The tricky part about the script I created was perfectly aligning the
pixels with the VCS kernel.  Right now I can match the 160 pixel
possibilities the VCS can generate with the 160 (actually 640) pixels in
the screengrab.  So as the pixels paint, they match up with the edges of
the playfield and sprites pretty well, and I can overlay an automatic
scanline indicator.

Attachment: ChessDiagram.png
Description: Binary data

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== Glenn Saunders  --3D Graphics / Videography / Web development--        ==
== krishna@xxxxxxxxxxxxxxx http://www.geocities.com/Hollywood/1698      ==
== Cyberpunks homepage      http://cyberpunks.atari.org	                 ==
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