John's Arcade Forum - Classic Arcade and Pinball Collecting and Restoring Discussion Forum - RETRO MAME - Nintendo Vs Forum

I have two games that have odd sprite errors. RC PRO AM, Dr. Mario, and Ninja Gaiden. The games play fine but they have little graphic glitches.

RC PRO AM has odd graphic issues on the bottom by the score
Ninja Gaiden has odd sprite issues around the main character
Dr. Mario looks great but after playing the game for 20 minutes or so the screen starts freaking out and sprites start to go haywire.

Is this bit rot on the ROMs?

This could be what you call bit rot. But not on all of the ROMs.
The CHR ROM which holds the image data may be corrupted in some areas (Most often the case I've seen). Also, try different motherboards with the games, the RAM might be bad (just a possibility). And whenever possible to prevent corruption of data on some of these ROMs, cover the UV windows on the chips. It is known that some fluorescent lights produce small amounts of UV light, which could screw up some bits.

I had a Vs. Castlevania with graphical glitches all over the place. I swapped the PPU and ROM to a Top Gun board and cleared them right up. While, I put the top gun back on the Castlevania board, and then it had the same issues.

As said before... CHR rom. I've seen replacements online, I've been wanting to experiment on mine. My Dr. Mario also has graphics problems. But, it uses two Eeproms. I know Steph at Hobbyroms has said he could burn me a set for it. May be worth looking in to.

Thanks guys! I have a ROM burner. I'll check the ROMs out and see if that fixes the issue. It's just odd that I would have 3 games that do this. It seems like bit rot isn't that likely.

ALSO, I should clarify, I am talking PC-10!!!!!

Ah, right!
Try swapping cards if you have a duplicate!
And don't forget about covering those UV windows on the EPROMS.