TECH: Pacman video

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Archived from groups: rec.games.video.arcade (More info?)

probably been covered a million times, but I'm just not getting it..

OK.. The game seems to run fine: the monsters & pac (the sprites) appear
normally, and follow the maze, but the maze is not there... Clearly the CPU
sees and properly reads and writes to the scratchpad RAM, but the screen
data is not selecting the proper character in the graphics ROM.

Could someone enlighten me on the path the data takes from video RAM to the
character ROMs? I've scoped all the lines, and I can find no bus
contention.

HELP!

Thanks,

Chris

 

[Guest]

Archived from groups: rec.games.video.arcade (More info?)

I should add that the screen is full of the dots that pac normally eats, but
they do not dissappear in the attract mode, and are at every position on the
screen (except the score area and credit area - those are some other garbage
character)