BIOS versions

BIOS Versions

The Dreamcast's boot firmware, often called the BIOS, handles startup, the built-in menu, and the initial disc check. While most modding does not require touching it, a basic understanding helps you make sense of behaviour you may see.

What the BIOS does

On power-up, the firmware shows the familiar swirl animation, checks the inserted disc, and presents the system menu where you set the clock and manage VMU data. The region information the console enforces is tied to this firmware.

BIOS and MIL-CD

The ability to boot MIL-CD discs — the foundation of no-mod homebrew — comes from the stock firmware on most retail units. A small number of late consoles had this capability removed, which is one reason a few units cannot boot burned discs even when the drive is healthy.

ODEs and the BIOS

An ODE presents disc images to the console as if they were real discs, so the standard firmware still performs the boot and region check. This is why region patching, whether manual or automatic, remains relevant even after installing an ODE.