ENIAC was built in 1946 by J.P. Eckert and J.W. Mauchly. It was the first machine of the first generation that used electron tubes in its operation. 17 500 vacuum lamps, 7200 crystal diodes, 1500 relays, 70 000 resistors, 10 000 capacitors, 1500 manual switches. Its ventilation was driven by two Chrysler engines – each with 34 hp. It weighed 27 tons and had dimensions of 30 x 2.4 x 0.9 m, occupied 167 m2. He consumed 160 kW of power. ENIAC could not work for too long without a break – the obstacle was a very large power needed to heat the lamps. The machine calculated ballistic tables, it was also used in works on the hydrogen bomb, weather forecasting, designing wind tunnels, researching cosmic rays; also used to study random numbers and analyze rounding errors; also calculated pi to the nearest one thousand decimal digits.