Using Mame to troubleshoot actual board sets

[Lutus]

This guy used Mame and recreated a bad chip for all the chips on his DK board set.  Then he compared the image to see what chip was wrong. 

I have a Donkey Kong 3 I am troubleshooting and want to do this for DK3.

Does anyone know how he manipulated 1 chip at a time (RAM/ROM/PRAM etc..)?

Can anyone explain how I could do this same thing?


http://www.brasington.org/arcade/tech/dk/

 

[BobA]

He assumed that a bad ROM would give all 1s so with that in mind he rewrote all the rom files with the data replaces with ones.   Then he ran MAME with the bad image of the rom.  Each rom was replaced one at a time and then restored so that only one file (rom location) was affected for each run of MAME.   You would have to use program such as a hex editor to change the data in the rom file to all 1s and use it instead of the good rom file.

[Lutus]

Alright, have started doing that and this is what has happened.

I determined, firstly, the bare minumum .bin files necessary to run the game.

I have started tinkering with the hex editor to replace a bunch of the bits and when running the game many interesting things have started happening.

BUT.... how do I know which addresses of which bin files correspond to the chips on the PCB?

[BobA]

You need the schematic and the manual to reference the part numbers and board loactions.  This should allow you to id which part is which when compared to the numbering used on the files in the DK3 zip.

[Lutus]

Ahh, I think I do know what you mean, I have both these items at home and will reference them and then keep experimenting with the hexeditor.  Will update once I know more.