1943

ENIAC

John Mauchly (1907–1980), J. Presper Eckert (1919–1995)

ENIAC was the first electronic computer, which means it computed with tubes rather than relays. Designed by John Mauchly and J. Presper Eckert at the Moore School of Electrical Engineering at the University of Pennsylvania, ENIAC had 17,468 vacuum tubes, was 8 feet (2.4 meters) high by 3 feet (0.9 meters) deep by 100 feet (30.5 meters) long, and weighed more than 30 tons.

ENIAC had an IBM punch-card reader for input and a card punch for output, but the machine had no memory for data or programs. Instead, numbers under calculation were kept in one of the computer’s 20 accumulators, each of which could store 10 decimal digits and perform addition or subtraction. Other hardware could perform multiplication, division, and even square roots. ENIAC wasn’t programmed in today’s sense. Instead, a set of panels had 1,200 10-position rotary switches that would energize different circuits in a specific sequence, causing electronic representations of numbers to flow through different parts of the machine at predetermined times, and leading the machine computation to take place.

ENIAC was built to perform complex ballistics calculations for the US Army, but John von Neumann (1903–1957) at the Manhattan Project learned about ENIAC, so the machine’s first official use was actually to perform computations for the development of the hydrogen bomb.

Ironically, the men who built the hardware never considered the need for, or the complexity of, programming the machine. They left the job of making the machine actually calculate to six human computers: Frances “Betty” Snyder Holberton (1917–2001), Betty “Jean” Jennings Bartik (1924–2011), Kathleen McNulty Mauchly Antonelli (1921–2006), Marlyn Wescoff Meltzer (1922–2008), Ruth Lichterman Teitelbaum (1924–1986), and Frances Bilas Spence (1922–2012).

Those women, some of the world’s first programmers, had to devise and then debug their own algorithms. But the women were not acknowledged in their own time. In 2014, Kathy Kleiman produced the documentary The Computers, which finally told the women’s story.

SEE ALSO First Recorded Use of the Word Computer (1613), EDVAC First Draft Report (1945)

ENIAC, the first electronic computer, was built to perform calculations for the US Army. Pictured operating the machine are Corporal Irwin Goldstein, Private First Class Homer Spence, Betty Jean Jennings, and Frances Bilas.