When searching for a reference full romset, you will encounter three distinct organization styles. Understanding these will save you storage space and configuration headaches.
This is where the "2003-Plus" distinction becomes vital. MAME 2003-Plus is a "fork"—an offshoot of the MAME project specifically optimized for speed and playability on lower-end hardware. It corresponds roughly to the MAME 0.78 codebase but is actively maintained by the Libretro community to include new features and bug fixes that the mainline MAME project has long since left behind in its pursuit of cycle-accurate simulation. For users with a Raspberry Pi 3 or a modest smartphone, MAME 2003-Plus offers the ideal balance of performance and compatibility. mame 2003plus reference full nonmerged romsets link
Understanding MAME 2003-Plus Reference Full Non-Merged Romsets When searching for a reference full romset, you
Support for hundreds of additional games (expanding the original list). Enhanced input configurations and cheat support. MAME 2003-Plus is a "fork"—an offshoot of the
Since the ROM set is custom to the core, you have two primary paths to get a fully compatible collection.