Moon Patrol - corrupt graphics.

Jeff F

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Donor 12 years: 2011-2022
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Any ideas? Could it be a RAM or does it look more like an addressing problem? I'm getting a working PCB set Sunday so at least I'll be able to swap in boards until I figure out what board is having problems.

Just thought I'd post this in case it looks familiar to anyone.

:beerchug:
 
I'd look for a stuck high-order address line in the vram area... program is running, so this looks isolated to video subsustem...
 
Thanks for the direction. :beerchug:


When I posted this I didn't realize Moon Patrol had a diagnostic mode. :rolleyes: Looks like the problem is on the scrolling video board so I'll start with the RAM there. Then it'll be onto the addressing chips.

It helps that I have a working boardset to compare measurements with now.
 
Made progress with this board but it's still not 100%. The 2128 on the scrolling video board was defective. Now I have undistorted graphics but the graphics are only drawn on the right side of the screen. Then anything that scrolls, scrolls across the undrawn area on the left.
 
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