1940 In1940, Samuel Williams and Stibitz complete a calculator which can operate on complex numbers, and give it the imaginative name of the Complex Number Calculator (CNC) later we call it Model I Relay Calculator. Stibitz stunned the group by performing calculations remotely on the CNC that located in New York, he used a telephone lines to connect. This telephone can switch parts for logic: 450 relays and 10 crossbar switches. Numbers are represented in "plus 3 BCD"; that is, for each decimal digit, 0 is represented by binary 0011, 1 by 0100, and so on up to 1100 for 9; this scheme requires fewer relays than straight BCD. Rather than requiring users to come to the machine to use it, the calculator is provided with three remote keyboards, at various places in the building, in the form of teletypes. Only one can be used at a time, and the output is automatically displayed on the same one. 1941 Konrad Zuse (German Engineer) completed the Z3.Z3 is the first o...
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