Finding a reliable and verified MAME 2003 Plus ROM set archive can be challenging. However, there are several sources to explore:
Most (95%+) are compatible with MAME 0.78, but updated and new games require specific 2003-Plus files. CHDs: Uses the same CHD v3 files as MAME 0.78. mame 2003 plus romset archive verified
Adds support for games that were unplayable or missing in original MAME 0.78 sets. Finding a reliable and verified MAME 2003 Plus