Penn’s ENIAC, the World’s First Electronic Computer, Turns 80

Computing now powers nearly every facet of modern life and industry. And the birthplace of the modern computer was not in Silicon Valley but at the University of Pennsylvania.

This new era in human problem-solving was launched in 1946, when Penn scientists J. Presper Eckert and John Mauchly built ENIAC, the world’s first general-purpose, electronic, programmable computer.

One of ENIAC’s most revolutionary contributions was its ability to be reprogrammed to solve complex numerical problems. Specifically, what set it apart from other machines of the time was that it could be rewired to perform different calculations rather than being fixed for a single task. ENIAC could execute “conditional branches” — operations that allowed it to switch between different calculations based on intermediate results. In other words, ENIAC could perform “if this, then that” operations.

Earlier machines were sophisticated but limited, relying on clunky gears and rotating shafts that had to physically mesh to perform a calculation. This reliance on the physical world limited their speed.

ENIAC, however, harnessed the flow of electrons. Using more than 17,000 vacuum tubes as near-instant switches, it was able to perform calculations far faster than mechanical relays, accelerating the development of the hydrogen bomb (known as the “Super”) and ushering in the digital age.

Although ENIAC, which is celebrating its 80th anniversary this week, no longer operates, four of its original 40 nine-foot-tall panels are on display at Penn Engineering’s Moore School Building — the site where modern computing began.

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Jean Bartik (left) and Frances Spence operating the ENIAC’s main control panel (Images: Courtesy of University Archives)