The anatomy of the Burroughs Calculator

The Burroughs Calculator is a mechanical marvel made in the twentieth years of the XX century. Its unique feature was the ability to display the result instantly after the key was pressed. The device was capable adding and subtracting ( using a "nines complement" method ) a 10 digit numbers. You can find more about how to use a full keyboard calculator on this page Operating a Comptometer

Inside the calculator you will find a set of number drums driven by the planetary gears responsible for tens carry.

Each of the drums is connected to the corresponding column of keys with a system of levers , tooth arc and the unidirectional clutch. The clutch allows the drums to be rotated only during the backward motion of the key.

The reset lever disconnects the coupling between the drums and then moves them to the zero position using cams.