Ladies and Gentlemen, Girls and Boys Behold: The Nordsieck Synchro Operated Differential Analyzer.

"As with other analog computers, each calculation required its own setup. You plugged in the tangle of patch cords to the left in a particular pattern. The cords served as the computer’s control program, with other parts of the program embodied and executed by the spinning disks, gears, rotating shafts, cranks, and the like. (You can read Nordsieck’s early description of the computer here [PDF] and his written instructions here [PDF]." - via IEEE Spectrum Magazine