Simple Hook-up?

Does anyone know a super simple game console hook-up? I don't really know much about circuit boards, and electronics, but I'd like to learn. What I mean by simple is: a power supply plug for it, AV cable plugin, an on/off switch, controller ports, and game cartridge port. To be specific, I'd like to be able to build a smaller, simpler version of a Sega Genesis, or N64, or whatever.

                                                            --- Thanks!!