Gameboy Development Forum

To be honest, I don't know how exactly bank switching affects the pins. The code I mentioned in post #8 should in theory do the same as the bank switching instruction, so it's worth to give it a try and see what happens. "In theory" because with GBDK you never know what happens when you tamper with the hardware.

Just out of curiostiy: Is there any documentation or something for Rainer Ziegler's program? And do the 16 kb programs you can start from the menu also work on a standalone basis without the menu (when you just put them in bank 0)?

Last edited by Jonas (2018-07-30 08:02:53)

JS7777 wrote:

Yes the tools works without the menu.

No, they don't.

The program or game must be assembled or compiled for the range 0x4000-0x7FFF and the values inside 0x0000-0x0150 (RET, RETI, Logo, Licensee, ROM size,..) must be at 0x4000-0x4150. So, write and test your cartridge at bank 0 and after testing add to all org statements 0x4000.

And now I do understand how it works. When you select a program from the menu, the menu simply switches to the respective bank and jumps to the starting point of the program (normally at address $0100 but in this case at $4100). For that purpose, however, the complete code of the program must be adjusted respectively. Otherwise, the first jump instruction would crash the program.