**ENIAC** which the acronym is “Electronic Numerical Integrator and Computer” was one of the very first electronic computers. It was Turing tested, all digital and able to solve several types of mathematical problems through programming.

ENIAC was designed to primarily calculate some technical based projects for the US Army, its first programs included studies to calculate artillery firing tables for the Ballistic Research Laboratory but also studies related to the feasibility of the thermonuclear weapon. **ENIAC** was formally installed and fully operational at the University of Pennsylvania on February 15, 1946 and was also named as a “Giant Brain” by the press of that era. It had a speed around one thousand times faster than that any previous electro-mechanical machine calculation devices; this calculation properties added with an all-purpose programmable computation generated excitement with the scientific press.

The combination of speed and programmable features allowed more scale to solve thousands of calculations for several kind of problems, as an example ENIAC can calculate a trajectory that took a human 20 hours in only 30 seconds (a 2400X increase in speed).

Designed as a modular computer based on individual panels to conduct different calculations, part of these panels were accumulators for add and subtract calculations but also can hold a ten-digit decimal number in memory, then numbers were passed between these units across several buses. To achieve its high speed, the panels had to send and receive numbers, compute, save the answer and trigger the next operations but without any moving parts.

The design was commanded by John Mauchly and J. Presper Eckert of the University of Pennsylvania, U.S. led and financed by the US Army Research and Development Command, managed by Major General Gladeon M. Barnes. The team of design engineers assisting the development included Robert F. Shaw (function tables), Jeffrey Chuan Chu (divider/square-rooter), Thomas Kite Sharpless (master programmer), Frank Mural (master programmer), Arthur Burks (multiplier), Harry Huskey (reader/printer) and Jack Davis (accumulators). ^{}In 1946, the researchers resigned from the University of Pennsylvania and formed the Eckert-Mauchly Computer Corporation.

ENIAC was enormous. It occupied the 50-by-30-foot basement of the Moore School, where its 40 panels were arranged, U-shaped, along three walls. Each of the units was about 2 feet wide by 2 feet deep by 8 feet high. With approximately 18,000 vacuum tubes, 70,000 resistors, 10,000 capacitors, 6,000 switches, and 1,500 relays, it was easily the most complex electronic system theretofore built. ENIAC ran continuously (in part to extend tube life), generating 150 kilowatts of heat, and could execute up to 5,000 additions per second, several orders of magnitude faster than its electromechanical predecessors. It and subsequent computers employing vacuum tubes are known as first-generation computers. (With 1,500 mechanical relays, ENIAC was still transitional to later, fully electronic computers.)

To enlist some of the contributions that the ENIAC support its development, was the involvement of the Alamos research laboratory where the mathematician John von Neumann ran the computations for the hydrogen bomb, amazingly this calculations required more than one million cards to be completed. Later on this computer was utilized for the “Monte Carlo method” to investigate the distance that neutrons would likely travel through different materials. John von Neumann and Stanislaw Ulam realized the speed of ENIAC would allow these calculations to be done much more quickly. The success of this project showed the value of Monte Carlo methods in science.^{}

A few months after ENIAC’s was unveiled in 1946, as part of “an extraordinary effort to jump-start research in the field”, ^{}the Pentagon invited an elite group of prominent celebrities in electronics and mathematics from the United States and Great Britain” ^{}to a series of forty-eight lectures given in Philadelphia, Pennsylvania; all together called *The Theory and Techniques for Design of Digital Computers*—more often named the Moore School Lectures. ^{} Half of these lectures were given by the #inventors of the ENIAC.^{}

Eckert and Mauchly started work on a new design in parallel, to be later called the EDVAC, which would be more simpler and even more powerful and in 1944 Eckert wrote his description of a memory unit (the mercury delay line) which would hold both the data and the program. John von Neumann, who was consulting for the Moore School on the EDVAC, sat in on the Moore School meetings at which the stored program concept was elaborated. Von Neumann wrote up an incomplete set of notes (*First Draft of a Report on the EDVAC*) which were intended to be used as an internal memorandum—describing, elaborating, and couching in formal logical language the ideas developed in the meetings. ENIAC administrator and security officer Herman Goldstine distributed copies of this *First Draft* to a number of government and educational institutions, spurring widespread interest in the construction of a new generation of electronic computing machines, including Electronic Delay Storage Automatic Calculator (EDSAC) at Cambridge University, England and SEAC at the U.S. Bureau of Standards.