ROMset compatibility with MAME 2003 The MAME 2003 core accepts MAME 0.78 ROMsets. Each version of an arcade emulator must be used with ROMs that have the same exact version number. For example, MAME 0.37b5 ROMsets are required by the MAME 2000 emulator, but MAME 0.37b5 sets will not work correctly with the MAME 2003 or MAME 2010 emulator cores.
Those cores require MAME 0.78 and MAME 0.139 ROM sets, respectively. File-not-found errors are the result of a ROMset that is wrong or incomplete, including if you're trying to run a 'Split' clone.zip without the parent.zip present.
'Non-Merged ROM' romset collections do not require parent.zips to be present. 'Full Non-Merged' romset collections do not require the parent.zip or the BIOS.zip; Full Non-Merged romsets are fully standalone. Multiple lightgun, steering wheel, and 'spinner/dial' devices MAME 2003 has support for multiple mice or touch devices in games that support trackballs, etc.
MAME 2003 also supports one or two spinners/dials via the 'Share 2 player dial controls across one X/Y device' core option. Directories • Some MAME games require data from an internal hard drive, CD-ROM, laserdisk, or other media in order to be emulated -- those forms of media are packaged as CHD files. CHD files should be copied to subfolders within the folder where the MAME ROM zips have been installed. E.g.: /libretro content dir/blitz/blitz.chd • Some games require an additional zip file with recorded sounds or music in order for audio to work correctly. Audio 'sample' files should be placed in subdirectories within /libretro system dir/mame2003/ e.g.: /libretro system dir/mame2003/samples/ • cheat and history metadata files should be moved from github's and placed within /libretro system dir/mame2003/ e.g.: /libretro system dir/mame2003/cheat.dat /libretro system dir/mame2003/history.dat • hiscore metadata is built into mame2003 and enabled by default, however external highscore data can also be used.