From the Abacus to the Stepped Drum Machine

Reckoning like the Romans or like the Europeans in the Middle Ages - that's no problem with the "Abacus". We shall learn to use the abacus, before taking a mighty leap in time, to the seventeenth century and the stepped drum machine which Gottfried Wilhelm Leibniz invented in 1670. His machine was the basis of many other calculating machines for three-hundred years.