John Presper Eckert was an American engineer who helped design and build ENIAC, the first general-purpose electronic digital computer. ENIAC (Electronic Numerical Integrator and Computer) was a Turing-complete, digital electronic computer built in 1946 at the University of Pennsylvania to calculate artillery firing tables for the United States Army's Ballistic Research Laboratory. It had over 18,000 vacuum tubes, weighed 30 tons, and took up 1,800 square feet.