ENIAC

ENIAC (/ˈɛniæk/; Electronic Numerical Integrator and Computer) was the first programmable, electronic, general-purpose digital computer, completed in 1945. Other computers had some of these features, but ENIAC was the first to have them all. It was Turing-complete and able to solve "a large class of numerical problems" through reprogramming.

ENIAC was designed by John Mauchly and J. Presper Eckert to calculate artillery firing tables for the United States Army's Ballistic Research Laboratory (which later became a part of the Army Research Laboratory). However, its first program was a study of the feasibility of the thermonuclear weapon.

ENIAC was completed in 1945 and first put to work for practical purposes on December 10, 1945.

ENIAC was formally dedicated at the University of Pennsylvania on February 15, 1946, having cost $487,000 (equivalent to $7,000,000 in 2024), and called a "Giant Brain" by the press. It had a speed on the order of one thousand times faster than that of electro-mechanical machines.

ENIAC was formally accepted by the U.S. Army Ordnance Corps in July 1946. It was transferred to Aberdeen Proving Ground in Aberdeen, Maryland in 1947, where it was in continuous operation until 1955.

ENIAC's design and construction was financed by the United States Army, Ordnance Corps, Research and Development Command, led by Major General Gladeon M. Barnes. The total cost was about $487,000, equivalent to $7,000,000 in 2024. The conception of ENIAC began in June 1941, when Friden calculators and differential analyzers were used by the United States Army Ordnance Department to compute firing tables for artillery, which was done by graduate students under John Mauchly's supervision. Mauchly began to wonder if electronics could be applied to mathematics for faster calculations. He partnered up with research associate J. Presper Eckert, as Mauchly wasn't an electronics expert, to draft an electronic computer that could work at an excellent pace. Later, in August 1942, Mauchly proposed an all-electronic calculating machine that could help the U.S. Army calculate complex ballistics tables. The U.S. Army Ordnance accepted their plan, giving the University of Pennsylvania a six-months research contract for $61,700. The construction contract was signed on June 5, 1943; work on the computer began in secret at the University of Pennsylvania's Moore School of Electrical Engineering the following month, under the code name "Project PX", with John Grist Brainerd as principal investigator. Herman H. Goldstine persuaded the Army to fund the project, which put him in charge to oversee it for them. Assembly for the computer began in June 1944. Later, in September of that year, Eckert and Mauchly completed their conception on the computer. Construction for the computer was complete in May 1945, and testing for it began at the Moore School. Later, in November of that year, the duo, along with John Brainerd and Herman Goldstine, issued the first confidential published report on the computer, which talks about how it worked and the methods by which it was programmed.

ENIAC was designed by Ursinus College physics professor John Mauchly and J. Presper Eckert of the University of Pennsylvania. 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). Significant development work was undertaken by the female mathematicians who handled the bulk of the ENIAC programming: Jean Jennings, Marlyn Wescoff, Ruth Lichterman, Betty Snyder, Frances Bilas, and Kay McNulty. In 1946, the researchers resigned from the University of Pennsylvania and formed the Eckert–Mauchly Computer Corporation.

ENIAC was a large, modular computer, composed of individual panels to perform different functions. Twenty of these modules were accumulators that could not only add and subtract, but hold a ten-digit decimal number in memory. Numbers were passed between these units across several general-purpose buses (or trays, as they were called). In order to achieve its high speed, the panels had to send and receive numbers, compute, save the answer and trigger the next operation, all without any moving parts. Key to its versatility was the ability to branch; it could trigger different operations, depending on the sign of a computed result.