Some messing around with undocumented VDP register (C0001E)

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TmEE co.(TM)
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Some messing around with undocumented VDP register (C0001E)

Post by TmEE co.(TM) » Tue May 05, 2009 12:47 pm

http://www.youtube.com/watch?v=SJ9_fNi-pM4

unstructured random messing around....

2nd controller was used to change bits, and it also controls the sprite.

I discovered one other thing (not seen in the video), when you move the sprite in lower right corner so some of the sprite is offscreen, you can get some constant lines being drawn to the screen, that seem to use colors from the sprite and the how the lines look depend on the sprite graphics too...... lot of fun...

my cam is dead so I cannot make more videos

If anyone wants, I can prepare that ROM for people with flashcarts to try.

the behaviour is identical on MD2 and MD1.
Mida sa loed ? Nagunii aru ei saa ;)
http://www.tmeeco.eu
Files of all broken links and images of mine are found here : http://www.tmeeco.eu/FileDen

HardWareMan
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Location: Kazakhstan, Pavlodar

Re: Some messing around with undocumented VDP register (C000

Post by HardWareMan » Wed May 06, 2009 3:23 am

TmEE co.(TM) wrote:If anyone wants, I can prepare that ROM for people with flashcarts to try.
Proceed, I'll try it.

TmEE co.(TM)
Very interested
Posts: 2370
Joined: Tue Dec 05, 2006 1:37 pm
Location: Estonia, Rapla City
Contact:

Post by TmEE co.(TM) » Wed May 06, 2009 2:56 pm

Not exactly same ROM, but code is :
http://www.fileden.com/files/2008/4/21/ ... FPLAYG.rar

Holding down A on 2nd pad will halt the ball, use d-pad to move... this all affects what will happen though since the code also sets the bits in that reg.

The C0001E reg gets ACBRLDU into the meaninful bits in that order (if it makes any sense).
Mida sa loed ? Nagunii aru ei saa ;)
http://www.tmeeco.eu
Files of all broken links and images of mine are found here : http://www.tmeeco.eu/FileDen

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