Unlike modern emulators that use a "one-size-fits-all" approach, MAME (Multiple Arcade Machine Emulator) requires a ROM set that matches the exact version of the emulator you are running.

Finding a reliable is essential for retro gaming enthusiasts using low-power devices like the Raspberry Pi, old Android phones, or the PlayStation Classic. This specific version, also known as the MAME 2003 reference set , is prized because it strikes a perfect balance between performance and compatibility. Why You Need the MAME 0.78 Rom Set

When downloading, you will typically encounter three types of sets: What's inside MAME Romset 0.78? - RetroPie Forum