Computer history starts in 1623,
when Wilhelm Schickard built mankind's
first automatic calculator.
Schickard's machine could perform basic
arithmetic operations on integer inputs.
His letters to Kepler,
discoverer of the laws of planetary motion,
explain the application of his "calculating clock"
to the computation of astronomical tables.
The non programmable Schickard machine was based on the
traditional decimal system.
Leibniz subsequently discovered
the more convenient binary system (1679), an essential
ingredient of the world's first working program controlled
computer, due to Zuse (1941).
