Games like Killer Instinct or Area 51 require both a ROM and a CHD.
The MAME 2003 Reference Set strikes the perfect chord between nostalgia and usability. By sticking to the 0.078 ROMs, you ensure that your arcade build remains stable, fast, and compatible with the widest range of devices possible. To help you get started with your specific setup: What are you planning to run these on? MAME 2003 Reference Set - MAME 0.078 ROMs- CHDs...
This is the most common format. The "clone" game depends on the "parent" game. You cannot delete the Pac-Man zip if you want to play Ms. Pac-Man . Games like Killer Instinct or Area 51 require
CHDs must be placed in a sub-folder named exactly like the ROM zip file. The Different Set Types: Full, Split, and Merged MAME 2003 Reference Set - MAME 0.078 ROMs- CHDs...