Here is my first GBA program I ever wrote — it’s just a simple color bar demo written in 100% thumb assembly code. It should assemble just fine under gas without needing any header files. I haven’t tested this in a while, but I’m pretty sure it still works 🙂
Again, due to limitations on wordpress.com, the file is named colorss.txt but you will need to rename it to colors.s after downloading.
Here is a simple little program that will dump the header of the cart that is in the GBA. You can send it over via MBV2, or if you start it from a flash cart, you can remove the cart and put another one in.
Here is another simple program — this one allows you to test all of the buttons on your GBA.