ENIAC, the first general-purpose electronic computer, weighed 30 tons and consumed as much electricity as 150 homes.

The Electronic Numerical Integrator and Computer (ENIAC) was designed by John Mauchly and J. Presper Eckert at the University of Pennsylvania's Moore School of Electrical Engineering. Construction began in 1943 during World War II, funded by the United States Army to calculate artillery firing tables. When formally dedicated on February 15, 1946, ENIAC cost approximately $487,000—equivalent to over $7 million in today's dollars.The machine's physical scale was staggering, occupying a room roughly 30 by 50 feet. It contained 17,468 vacuum tubes, 7,200 crystal diodes, 1,500 relays, and 70,000 resistors. These components generated enormous heat, requiring a dedicated forced-air cooling system to prevent the tubes from burning out frequently.ENIAC consumed 150 kilowatts of electricity—enough to dim the lights of nearby Philadelphia neighborhoods when powered on. Despite its massive footprint, it could only perform about 5,000 additions or 385 multiplications per second. This was groundbreaking at the time, but incredibly slow compared to the billions of operations per second performed by modern microprocessors.The system lacked a modern operating system and required manual programming by flipping switches and plugging in cables. Six women, including Kay McNulty and Betty Jennings, served as the primary programmers, mapping out complex logical paths for the machine. ENIAC remained in operation until October 2, 1955, marking a pivotal moment in the digital revolution.