Sega Dreamcast Bios Files

: On systems like the Steam Deck, BIOS files are generally placed in the /Emulation/bios/ directory. Regional and Custom BIOS

The Dreamcast emulator has a "HLE" mode that works for about 60% of the library. But for the weird stuff—the Seaman voice recognition, the VMU mini-games, the custom sprite rendering in Jet Set Radio —you still need the real BIOS. sega dreamcast bios files

This is the most important section.