d21lewis on 04 April 2008
I'm sure it's got a purpose. Conversely, the Nes, SNes, PS1, and Sega Master System all had inputs. When the systems were released, these inputs would serve as the systems ability to expand. To my knowledge, these ports, jacks, etc. were never officially used. Maybe that's how the XBOX's input port went too. I'm pulling this answer out of my ass, though.
