MAME Path Handling

MAME has a specific order it uses when checking for user files such as ROM sets and cheat files.

Order of Path Loading

Let’s use an example of the cheat file for AfterBurner 2 for Sega Genesis/MegaDrive (aburner2 in the megadrive softlist), and your cheatpath is set to “cheat” (as per the default) – this is how MAME will search for that cheat file:

  1. cheat/megadriv/aburner2.xml
  2. cheat/ -> aburner2.xml Notice that it checks for a .ZIP file first before a .7Z file.
  3. cheat/ -> <arbitrary path>/aburner2.xml It will look for the first (if any) aburner2.xml file it can find inside that zip, no matter what the path is.
  4. -> megadriv/aburner2.xml Now it is specifically looking for the file and folder combination, but inside the file.
  5. -> <arbitrary path>/megadriv/aburner2.xml Like before, except looking for the first (if any) aburner2.xml inside a megadriv folder inside the zip.
  6. cheat/megadriv.7z -> aburner2.xml Now we start checking 7ZIP files.
  7. cheat/megadriv.7z -> <arbitrary path>/aburner2.xml
  8. cheat.7z -> megadriv/aburner2.xml
  9. cheat.7z -> <arbitrary path>/megadriv/aburner2.xml Similar to zip, except now 7ZIP files.

[todo: ROM set loading is slightly more complicated, adding CRC. Get that documented in the next day or two.]