Qualla: ENIAC

ENIAC: Introduction

Sun, 22 Feb 2026 00:00:00 GMT

Photo credit JJonahJackalope, CC BY-SA 4.0. The press called it a "Giant Brain." When ENIAC was unveiled at the University of Pennsylvania on February 15, 1946, the assembled reporters struggled to convey what they were looking at: forty black panels arranged in a U-shape, filling an entire room, containing 18,000 vacuum tubes, 70,000 resistors, and roughly five million hand-soldered joints. It weighed more than 30 tons and consumed 150 kilowatts of electricity. Yet this massive machine could perform 5,000 additions per second -- a thousand times faster than any electromechanical calculator in existence. ENIAC was the first programmable, electronic, general-purpose digital computer, and it was born in Philadelphia.

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Image: JJonahJackalope | CC BY-SA 4.0

ENIAC: Project PX

Sun, 22 Feb 2026 00:00:00 GMT

Photo credit Unidentified U.S. Army photographer, Public domain. The idea for ENIAC took root in June 1941, when physicist John Mauchly watched graduate students hunched over Friden calculators, laboriously computing artillery firing tables for the U.S. Army. He wondered if electronics could do the job faster. Partnering with electrical engine...

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Image: Unidentified U.S. Army photographer | Public domain

ENIAC: The Women Who Programmed the Future

Sun, 22 Feb 2026 00:00:00 GMT

Photo credit Bubba73, CC BY-SA 3.0. Six women -- Kay McNulty, Jean Jennings, Betty Snyder, Marlyn Wescoff, Fran Bilas, and Ruth Lichterman -- were selected from a pool of about two hundred female "computers" at the Moore School to become ENIAC's first programmers. They studied the machine's blueprints, logic, and p...

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Image: Bubba73 | CC BY-SA 3.0

ENIAC: A Machine That Changed Everything

Sun, 22 Feb 2026 00:00:00 GMT

Photo credit Bubba73, CC BY-SA 3.0. ENIAC's first real task was not the artillery calculations it was designed for. Instead, John von Neumann commandeered the machine in December 1945 to run calculations for the hydrogen bomb program at Los Alamos. Von Neumann and Stanislaw Ulam also used ENIAC to pioneer the Monte...

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Image: Bubba73 | CC BY-SA 3.0

ENIAC: Tubes, Crashes, and Endurance

Sun, 22 Feb 2026 00:00:00 GMT

Photo credit Bubba73 (Jud McCranie), CC BY-SA 3.0. Running ENIAC was an act of perpetual maintenance. Several vacuum tubes burned out almost every day, rendering the machine nonfunctional roughly half the time in its early years. Engineers discovered that most failures occurred during warm-up and cool-down, when thermal stress wa...

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Image: Bubba73 (Jud McCranie) | CC BY-SA 3.0

ENIAC: Scattered Relics of the Giant Brain

Sun, 22 Feb 2026 00:00:00 GMT

Photo credit Bubba73, CC BY-SA 3.0. Today, ENIAC's forty original panels are dispersed across institutions nationwide. The University of Pennsylvania holds four panels and a function table in its School of Engineering. The Smithsonian's National Museum of American History houses several more. The Computer History M...

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Image: Bubba73 | CC BY-SA 3.0