[deaddodo]

Not the cart ID, you're looking in the cart header at byte 0147 for the actual hardware (MBC1, MBC2, MMM01, etc) functionality in conjunction with bytes 0148 (ROM size) and 0149 (RAM size) for specific bank sizing/mapping.

[tnecniv]

Yeah that's what I meant. It's been more than 5 years so I didn't remember the exact details. Thanks for the specifics!