USA - John Atanasoff - 1940


Designed and part-completed a special-purpose Electronic Digital Computer for solving sets of linear simultaneous equations. His work was known to several people in the USA and consequently his ideas may have had some influence over the design of the early American machines.


Germany - Konrad Zuse - 1941


Built the first operational program-controlled computer - this was an electro-mechanical device, controlled by punched tape.


Helmut Schreyer, a colleague of Zuse’s, designed an electronic version of Zuse’s electro-mechanical unit. However, this work was not known outside Germany at the time and so Zuse did not influence the British or US machines.


Built the first operational program-controlled computer - this was an electro-mechanical device, controlled by punched tape.


Helmut Schreyer, a colleague of Zuse’s, designed an electronic version of Zuse’s electro-mechanical unit. However, this work was not known outside Germany at the time and so Zuse did not influence the British or US machines.


USA - Howard Aiken - 1943


Mark I program controlled electro-mechanical computer.


USA - George Stibitz - 1944


Model III programmed electro-mechanical computer.


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None of these machines worked at electronic speeds or had conditional branching, a stored program or any self-programming facility. However, the Mark I and Model III (and other machines produced by Aiken and Stibitz) certainly assisted later on in the development of ENIAC and the EDVAC concept (although initially the designers were ignorant of Aiken's work). Furthermore, some very advanced features were included (e.g. remote operation, floating point).


But mechanical and electro-mechanical machines were not fast enough. Only the speed offered by electronic calculation was enough to be significantly faster than manual calculation.

EARLY PIONEERS - 2