> Unlike computers, most arcade platforms are "closed" systems with no provision for > plugging in anything except controls and a monitor. So if you're talking about an > arcade game you will probably not need any "device ROMs".
You'll need device ROMs for the Namco C chips for many Namco arcade games, and for Qsound for a bunch of Capcom games. It all depends on the game and whether it has any common devices shared with other games.