Raster split and $9002

Basic and Machine Language

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pixel
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Re: Raster split and $9002

Postby pixel » Sat Aug 26, 2017 6:57 am

tokra wrote:
We need a "VIC raster explorer"…

Sounds like your next project :D

Well, would be exciting but the next thing, I guess, is a finished Ultimem filemenu. Wanna get really busy with the retro tape manufacture.
A man without talent or ambition is most easily pleased. Others set his path and he is content.
https://github.com/SvenMichaelKlose

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Mike
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Re: Raster split and $9002

Postby Mike » Sat Aug 26, 2017 10:46 am

tokra wrote:(are you listening, Mike?)

Yes.

...

:lol:

(... > off to continue with the new raster paper ... ;) )

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beamrider
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Re: Raster split and $9002

Postby beamrider » Sat Aug 26, 2017 12:33 pm

Ok some progress... :D

Thanks to the discovery by Tokra :D that position 68 gives identical behaviour on the real h/w and VICE - I have modified my code to achieve a stable result on both using this value. I've also eliminated the artefacts present above the lettering in ex4 (real h/w) by setting that line of the color RAM to the same colour as the background within the 1st raster split and then restoring it to the colour needed for the scrolling region in the VBI

I now just need to work out how to get more lines of text without flickering, although two would provide a bare minimum of information for some games if this proves impossible.

See attached ex6..(btw there's no screen jitter during scrolling on real h/w for those that only have VICE, just a small hiccup on direction change due to a bug/defficiency in my code)

btw, you can also increase[6]/decrease[4]/reset[2] the black bar raster timing delay on this version using the keyboard.
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groepaz
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Re: Raster split and $9002

Postby groepaz » Sun Aug 27, 2017 9:43 am

i have slightly edited tokras test program and added it to the VICE testrepo here

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beamrider
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Re: Raster split and $9002

Postby beamrider » Sun Oct 29, 2017 1:57 pm

Perhaps this analysis of the hardware can add some light to this riddle?


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