Sega Master System BIOS

Sega Master System BIOS is a system booter, developed and released by Sega through 1986-1993.

Snail Maze

Snail Maze is a maze game, developed and released by Sega, in 1986. It was available in nearly all SMS1 models, which can be accessed by holding Up + 1 + 2 buttons at the Master System logo.

BIOS versions

SMS1

M404: Prototype. No game built-in, run only two games (the Japanese cartridge of Fantasy Zone and Choplifter);
V1.0: Prototype. No game built-in, Snail Maze can be accessed with the code, but is unfinished;
V1.3: No game built-in, Snail Maze can be accessed;
V2.0: Uncommon version. No game built-in, Snail Maze can be accessed, is the only Overseas SMS to be region-free;
V2.1: Japan only. No game built-in, Snail Maze is unavailable, features a Space Harrier theme which makes use of both SEGAVDP PSG and YM2413, region-free;
V2.4: Hang-On/Safari Hunt is built-in, Snail Maze can be accessed;
V3.4: Hang-On is built-in, Snail Maze can be accessed;
V4.4: Missile Defense 3-D is built-in, Snail Maze can be accessed.

SMS2

1st version (USA, Europe, Brazil, South Korea, Taiwan and East Asia): Alex Kidd in Miracle World is built-in, this version removes the onigiri and is replaced with a hamburger instead. It is also built-in onto Samsung Gam*Boy II;
2nd version (Europe and Brazil): Sonic the Hedgehog is built-in.