I have available a cartridge flasher for Game Boy to program these cartridges or make backups from original cartridges. Gameboy Programming Resources: (English).
Remember before writing the cartridge you need to erase it. You need to select these parameters to make a correct writing: It's also compatible with Game Boy Advance (and Advance SP) but running DMG/Pocket and Color games. This Flash Cart is a programmable cartridge to program your own games compatible with Game Boy DMG/Pocket and Color.
If you are interested in a 4MB ROM cartridge you can find it here. ¡NEW REVISION! With FRAM Memory, more than 151-year save game data retention at +65✬ without any battery
