Note: MAME 0.78 was the transition period for CHD (Compressed Hunks of Data) for games like Killer Instinct and Gauntlet Legends. The "Plus" update often ignores CHDs to save space. If you see missing CHD errors, you can safely disable CHD checking in the ROM manager. MAME Plus 0.78 runs those games slower anyway.
Cause: The Plus update uses a different NeoGeo BIOS (Universe BIOS v2.3 or a hacked decrypted BIOS).
Fix: Extract the neogeo.zip from your update pack, not from your standard set. Replace it entirely. mame 078 plus romset upd
For purists, newer is always better. MAME today is at version 0.260+. However, the early 2000s represented a sweet spot for emulation: Note: MAME 0