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February 14, 1946:  ENIAC is Unveiled

J. Presper Eckert and John Mauchly debut the Electronic Numerical Integrator and Computer (ENIAC). 17,468 vacuum tubes at 100,000 pulses/second. It was part of a $400,000 contract from the U.S. Army.


ENIAC (pron.: /ˈini.æk/ or /ˈɛni.æk/; 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 full range of computing problems.


ENIAC was designed to calculate artillery firing tables for the United States Army’s Ballistic Research Laboratory.  When ENIAC was announced in 1946 it was heralded in the press as a “Giant Brain”.   It had a speed of one thousand times that of electro-mechanical machines. This mathematical power, coupled with general-purpose programmability, excited scientists and industrialists.

Upon being completed, ENIAC contained 17,458 vacuum tubes, 7,200 crystal diodes, 1,500 relays, 70,000 resistors, 10,000 capacitors, and 5 million hand-soldered joints. The total power consumption was a whopping 160 kilowatts. There was even a rumor that when turned on the ENIAC caused the city of Philadelphia to experience brownouts, however, this was first reported incorrectly by the Philadelphia Bulletin in 1946 and since then has become an urban myth.  In one second, the ENIAC could perform 5,000 additions, 357 multiplications, or 38 divisions.


ENIAC was conceived and designed by 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), Arthur Burks (multiplier), Harry Huskey (reader/printer) and Jack Davis (accumulators). ENIAC was named an IEEE Milestone in 1987.


Eckert & Mauchly

ENIAC was the world’s first general-purpose electronic computer, but its reliance on vacuum tubes initially proved troublesome. In its early years, several tubes would burn out every day, leaving the computer inoperable for about half the time it was on. One of the reasons ENIAC was never shut off was because the main cause of vacuum tube failures was turning it on – the warm-up and cool-down periods created the most thermal stress.

Programming the ENIAC consisted of operating a massive series of plugs and switches. It took several days to input and run programs on the ENIAC. This said, ENIAC’s power (at the time) was still marvelous; It could perform the functions that one man would spend 20 hours on in around 15 minutes.


The original programmers of ENIAC computer were women. The most famous of the group was Jean Jennings Bartik (originally Betty Jennings). The other five women were Kay McNulty, Betty Snyder, Marlyn Wescoff, Fran Bilas, and Ruth Lichterman. All six have been inducted into the Women in Technology International Hall of Fame. When the U.S. Army introduced the ENIAC to the public, it introduced the inventors (Dr. John Mauchly and J. Presper Eckert), but it never introduced the female programmers.

Jean Bartic

Jean Bartic

Jean Bartik, one of the earliest pioneering women in technology, talks about her memories of breaking into the then new field of computer science and working on the ENIAC in the 1940’s


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