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Author Topic: Crazy Climber  (Read 2632 times)
tim
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« on: November 20, 2005, 04:59:12 PM »

Symptom
On first power-up, the Crazy Climber logo is all scrambled and flashing. At the first gameplay screen, the
Nichibutsu logo above the building door is also screwy. After a few seconds, a sort of grid of characters
flashes on screen and the graphics return to normal. This is consistant and happens the same way every time
you power on.

Tests
A peek at the MAME driver shows a seperate bit of RAM for large sprites. The Crazy Climber logo sounds like
a large sprite, all right. The MAME driver doesn't specifiy which ROMs hold the large sprites, so I experiment
by filling the graphics ROMs, one by one, with all FF's and see what graphics it screws up in MAME. It screws
up the CC logo when I fill either CC01 or CC02 with FF's. A look at the schematics shows the section with those
two ROMs is very straightforward. There's a couple 2101 RAM chips, the two ROMs, 5-6 TTL chips and out
to the screen it goes. Swapping the 2101's causes the scrambledness to change. Booting with the RAMs removed
causes the game to show big chunks of scrambledness in place of the logo. Pulling low a few pins on the
supporting logic chips either causes the graphics to disappear or have lines go through, but not make things
go all scrambly like the RAM. Gotta be the RAM.

Fix
Dug around and found another 256*4 RAM chip (a 93422), so I tried it in place of the 2101 in 5C. Bingo.
Logged
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