.GB File Format – Header codes

Cartridge type (0x147)

The hardware on the cartridge: the memory bank controller (MBC) that switches ROM and RAM banks, and extras such as battery-backed RAM (for saved games), a real-time clock (TIMER), a rumble motor or sensors.

ROM size (0x148)

For the standard codes the size is 32 KiB × 2^code, and the number of 16 KiB banks is 2^{code + 1}.

RAM size (0x149)

Must be 0x00 when the cartridge type has no “RAM” in its name. MBC2 cartridges also use 0x00, because their RAM is inside the controller.

Destination code (0x14A)

New licensee codes (0x144–0x145)

Two ASCII characters, read only when the old licensee code is 0x33. The code is written as text, so publisher 01 is the bytes 30 31.

Old licensee codes (0x14B)

One byte. 0x33 means the publisher is given by the new licensee code instead (and is required for Super Game Boy functions).

Sources

• The Cartridge Header – Pan Docs: the cartridge type, ROM size, RAM size, destination and both licensee code tables
• MBC1, MBC2, MBC3, MBC5, MBC6, MBC7, MMM01, HuC1, HuC3 – Pan Docs’ controller pages, for the capacities and extras in the type descriptions