Take a moment to look at your cellphone. Chances are, it’s “smarter” than the first electronic computer ever built. And somewhat smaller, too, considering the ENIAC (short for Electronic Numerical Integrator And Computer) took up a whole floor and weighed a whopping 27 tons. But for its time, it was the most stupendous piece of technology – calculating in minutes the speed and direction of artillery fire that used to take the army’s best minds hours and even days to plan.

On this day, February 15, in 1946, following a public unveiling the night before, the ENIAC was officially dedicated at the University of Pennsylvania.

Tempting though it may be to imagine ENIAC in modern terms, it in fact bore little resemblance to the computers of today. For one, there was no keyboard, or a screen. Commands to the computer were fed via Hollerith cards – punched cards encoding information – that were mechanically read and translated into computer code. Results of the calculations were also output on IBM punch cards, or alternatively on sheets of perforated paper.