The BIOS (Basic Input/Output System) is a set of firmware that controls the basic functions of a computer or console, such as initializing hardware components and providing a interface for the operating system.
The Sega Dreamcast uses a BIOS file to boot up and operate. The BIOS file for the Dreamcast is usually stored on a chip on the motherboard, but it can also be loaded from a file on a storage device. sega dreamcast bios files
You're looking for Sega Dreamcast BIOS files. The BIOS (Basic Input/Output System) is a set