Possible to Edit Game Roms?

[AmericanDemon]

I was playing X-Men today and thought it would be cool to update the clothing on the characters.  I know that in some NES Emulators you can go in and make changes.  Has anyone here done anything similar or know a way that it could be done for the arcade roms?

[maraxle]

I remember an old utility that let you change things in the (Ms.) Pac-Man roms, so it is possible.

[Crazy Cooter]

http://www.arcadecontrols.org/yabbse/index.php?board=3;action=display;threadid=25177

Howard is doing it.

[DaemonCollector]

http://www.arcadecontrols.org/yabbse/index.php?board=3;action=display;threadid=25177

Howard is doing it.

How is that anything like what he's talkin about? Howard is writing a stand alone game. You should be able to change the graphics though, its just a matter of figuring out how they are stored...maybe replacing the code in one of the roms files.

[ericball]

Hacks of this kind are certainly possible.  You first have to identify which ROMs the graphics are stored in and what format (bit and byte layout/organization) they are stored in.  Then you need to fix any checksums which may exist to make such changes difficult.  There may be other complications like fixed palettes and collision detection.

Some of that may be easier if you are able to use the MAME source, or recompile it with custom debugging and tracing.

Possible, yes, but not generically simple unless you are re-implementing a hack someone else has done.

[AmericanDemon]

Gotcha.  It appears as if this may be more difficult than I am wanting to do.    I mean I can live with old school costumes.  

[ften]

   You can do a search in Google for pages about rom hacking by searching on "IPS ROMs" or "IPS patching". IPS stands for International Patching System, just in case you were wondering.
   Also Zophar.net has a Utility section specifically for hacking graphics on ROMs.
http://www.zophar.net/utilities/graphics.html
   This is a specific arcade rom hacking Utility.... although a little dated.
http://www.cis.rit.edu/~jerry/Software/turacoCL/classic/

Hope that helped some.

-FTen

[AmericanDemon]

Whoa thanks!  Lots of stuff to read up on now.  

[Crazy Cooter]

How is that anything like what he's talkin about? Howard is writing a stand alone game.

So wouldn't he be a good person to talk to about manipulating the rom files?  I would think he'd know how things are stored and what proggies to check out.