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Missile Command - Graphics Troubles


SNESNESCUBE64

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This was a fun one as it was very interesting problem. The game itself worked suprisingly. However, there were issues with the graphics. 

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To me, this looks like an addressing error, as the game is fine but the graphics aren't quite there. I figured that it was a problem in the decoding. As shown in the schematic snippet below, this 7442 helps control which ROM bank, RAM, POKEY sound chip, or the user inputs like the trackball.

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Ultimately the bad chip ended up being this 7442. It's always nice when repairs are quick. Unfortunately, I don't have a way to test everything at the momment. For example, I don't have a trackball to test input with. I also didn't bother hooking up RGB since black and white composite was there through test points. Maybe there will be a second part depending on whether or not these things work correctly. Other than that, it just needs a burn in test, then it will be good to go.

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