Oldest system i both own and play would have to be intellivision. I dont spend alot of time playing it but i break it out more than my other pre nes systems. I just bought an RCA Studio 2 which im thinking wont get much use after the initial session, it is renowned for being awful lol. Oh and it doesnt have the switchbox and uses a power system similar to the 5200 where the power comes from the switch box luckily i did find a schematic for the box so i can just take a stab at building my own. I do actually break out and play some older handhelds though i personally love my coleco electronic quarter back handheld.