What does the MBV2 cable do?
The MBV2 (MultiBoot Version 2) is a cable that connects to a PC parallel port and to the link port on the GameBoy Advance itself. It allows you to test small GBA programs (256K bytes or less), that you have created yourself, on real GBA hardware, or you can use it to program flash carts (only GBA flash carts, no GB/GBC flash carts). It takes advantage of the fact that each GameBoy Advance has a built-in boot algorithm for loading code over the link port into external WRAM (256k bytes) and then executing this code. (External WRAM is actually inside of the GBA itself.) As such, no cart is required to be installed in the GBA to use this cable.
