At the end of the day, a bootloader is just memcpy, and a jump (with a few details like setting up a stack, any serial ports etc). You usually can have quite a

At the end of the day, a bootloader is just memcpy, and a jump (with a few details like setting up a stack, any serial ports etc). You usually can have quite a bit of help by looking at the generated code from your compiler that sets up a simple 'main(...){ while(1); }' program. Often it'll be in your toolchain as a .S file or similar.