Electronic Numerical Integrator And Computer or ENIAC was the first general-purpose electronic computer. Financed by the United States Army during World War II, John Mauchly and John Presper Eckert of the University of Pennsylvania, developed the ENIAC I. On February 15, 1946, ENIAC was formally dedicated at the University of Pennsylvania and Press heralded as a "Giant Brain" having a speed which is one thousand times faster than electro-mechanical machines of that time.Scientists and industrialists were excited with this computational power which is coupled with general purpose programmability. ENIAC has a 2400X increase in speed as once it calculated a trajectory, that took a human 20 hours, in 30 seconds. Thousands more calculations for problems were allowed with this combination of speed and programmability.

"...With the advent of everyday use of elaborate calculations, speed has become paramount to such a high degree that there is no machine on the market today capable of satisfying the full demand of modern computational methods." - from the ENIAC patent (U.S.#3,120,606) filed on June 26, 1947.


Specification of the Machine : 70,000 resistors, 6,000 manual switches, 1,500 relays, 10,000 capacitors, 5 million soldered joints, 17,468 vacuum tubes, 7200 crystal diodes. It weighed more than 30 short tons (27 t), was roughly 8 by 3 by 100 feet (2.4 m × 0.9 m × 30 m), took up 1800 square feet (167 m2), and consumed 150 kW of power. Input was possible from an IBM card reader, and an IBM card punch was used for output. These cards could be used to produce printed output offline using an IBM accounting machine, such as the IBM 405. Because of its high consumption of power, a rumour was floated that whenever the computer was switched on, lights in Philadelphia dimmed.

Common octal base radio tubes were used in ENIAC. While in logic functions 6L7's, 6SJ7's, 6SA7's and 6AC7's were used, the decimal accumulators were made of 6SN7 flip-flops. Numerous 6L6's and 6V6's served as line drivers to drive pulses through cables between rack assemblies. Kay McNulty, Betty Jennings, Betty Snyder, Marlyn Wescoff, Fran Bilas and Ruth Lichterman, ENIAC's six primary programmers, developed an understanding of ENIAC's inner workings and also determined how to input ENIAC programs. ENIAC was named an IEEE Milestone in 1987. The ENIAC celebrated its 70th anniversary on February 15, 2016.