The Master System and later Game Gear revisions include a BIOS ROM which is activated in the ROM area of the memory map on boot. See BIOSes for more information on this software's operation.

The BIOS is connected much as a hard-wired cartridge ROM - where necessary, it includes an integrated mapper. It may be activated using port $3E.

The first version of the Game Gear, the Mark III and all SG-1000 and SC-3000 variants have no BIOS.

See also:

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