Invention of the First computer
(Electronic Numerical Integrator And Computer) was the first electronic general-purpose computer. It was Turing-complete, digital, and capable of being reprogrammed to solve "a large class of numerical problems".ENIAC could discriminate the sign of a number, compare quantities for equality, add, subtract, multiply, divide, and extract square roots. ENIAC stored a maximum of twenty 10-digit decimal numbers. Its accumulators combined the functions of an adding machine and storage unit. No central memory until existed. Storage was localized within the functioning units of the computer.The primary aim of the designers was to achieve speed by making ENIAC as all-electronic as possible. The only mechanical elements in the final product were actually external to the calculator itself. These were an IBM card reader for input, a card punch for output, and the 1,500 associated relays.
The ENIAC was placed in operation at the Moore School, component by component, beginning with the cycling unit and an accumulator in June 1944. This was followed in rapid succession by the initiating unit and function tables in September 1945 and the divider and square-root unit in October 1945. Final assembly took place during the fall of 1945.
The accumulator was an essential element in all of ENIAC's arithmetic operations. Addition required two accumulators--one transferring its contents to the other. Subtraction, accomplished by a complement-and-add process, also used two accumulators. In normal multiplication, four accumulators stored the multiplier and multiplicand and accumulated the partial products. In division they shifted the remainder and stored the numerator, denominator, and quotient. The function table utilized the accumulators for storage of the argument and accumulation of the function value.
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