Fun Nintendo Hardware Fact:

During the switch from the Game Boy to Game Boy Advance, the line of handheld consoles saw a change in CPU architecture, from an Intel 8080 inspired architecture to ARM. Nintendo wanted the GBA to be backwards compatible with Game Boy and Game Boy Colour games, but the new CPU couldn't realistically run older game ROMs by itself. So the GBA actually has two CPUs. The new ARM processor, and a copy of the Game Boy's CPU exclusively for running older cartridges.