Not to be a party pooper, but In order for a Gameboy game to work, you have to include a binary blob which is (if I recall correctly) the bitmap image of "Nintendo" that scrolls up the screen when you power on the unit with a cartridge in it. A game won't work without it. It's both a copyright and trademark leverage to enforce Nintendo's licensing terms on developers. At least that's the way it was way back in the day when I made a foray into game development. Have they come up with a "jailbreak" for Gameboys that don't require that image?
@firstname.lastname@example.org I don't know the answer to your question. I have a trivial little program that draws text on the page that doesn't have the blob you speak of which runs fine in an emulator and on actual hardware via a flash cart. I will dig more into it though, you are probably correct though
It's a block of bytes that appears as a "header" in your flash cart's memory. It's static, so it could be easily inserted by your tools during link time. In the old days, I actually had an asm file with the appropriate bytes linked into my project. I turned up this info on the header: http://www.enliten.force9.co.uk/gameboy/carthead.htm