1948: valve plug-in unit and the IBM 604
Introduction
The IBM 604 is the first electronic calculator - realized with tubes. The calculating unit is nowadays a fundamental part of modern processors and has the property to calculate arithmetic (such as addition, subtraction) and logical (eg. AND-logic, negation) functions. To accomplish this several tubes are connected in a circuit diagram together.
Example AND-logic
The result C is only true (“1”) at the time when both input signals A and B are true (“1”), otherwise the result is FALSE (“0”).
