You mean one of the development systems? i can't remember all the different dev versions (there's at least three which share the Gamecube shape), but if i remember correctly, the red cube has a cart slot on the top of it. It uses special carts, and can hold up to four (each holding the same as a GOD). The carts emulate GODs in every way in order to determine real world performance without have to burn an NR disk.