MBC1 Cartridge Controller

[PHenegan]

https://gbdev.io/pandocs/MBC1.html#00003fff--rom-bank-x0-read-only

^^ Using this for documentation but there is some conflicting information:

In particular the banking mode is confusing me:

In its default configuration, MBC1 supports up to 512 KiB ROM with up to 32 KiB of banked RAM.

The banking mode can be: 0 = simple (default): 0000–3FFF and A000–BFFF are locked to bank 0 of ROM and SRAM respectively. 1 = advanced: 0000–3FFF and A000-BFFF can be bank-switched via the 4000–5FFF register.

Basically - the only way to access banks where the lower 5 bits are 0 (bank 32/0x20, 64/0x40, 96/0x60, 128/0x80) is by first writing to the bank, and then switching the mode of the cartridge so that it switches the first half of the ROM.

[PHenegan]

Note about reading from the ROM

This assumes there are more than 32 banks:

• Whenever it is in RAM mode, the first half should be switched based on the RAM bank.
• The second half should always include the RAM bank in the access regardless of which banking mode the cartridge is in.