In 1946, John Mauchly and John Presper Eckert developed the ENIAC I (Electrical Numerical Integrator and Calculator). The U.S. military sponsored their research; they needed a calculating device for writing artillery-firing tables (the settings used for different weapons under varied conditions for target accuracy). The Ballistics Research Laboratory heard about John Mauchly's research at the University of Pennsylvania's Moore School of Electrical Engineering. Mauchly had previously created several calculating machines, some with small electric motors inside. In 1942 he had begun designing a better calculating machine based on the work of John Atanasoff, which would use vacuum tubes to speed up calculations.
On May 31, 1943, the military commission on the new computer began; Mauchly was the chief consultant and Eckert was the chief engineer. Eckert was a graduate student studying at the Moore School when he met John Mauchly in 1943. It took the team about one year to design the ENIAC and 18 months and 500,000 tax dollars to build it. By that time, the war was over. The ENIAC was still put to work by the military doing calculations for the design of a hydrogen bomb, weather prediction, cosmic-ray studies, thermal ignition, random-number studies and wind-tunnel design.
The ENIAC contained 17,468 vacuum tubes, along with 70,000 resistors, 10,000 capacitors, 1,500 relays, 6,000 manual switches and 5 million soldered joints. It covered 1800 square feet of floor space, weighed 30 tons, consumed 160 kilowatts of electrical power, and, when turned on, caused the city of Philadelphia to experience brownouts.
In one second, the ENIAC (one thousand times faster than any other calculating machine to date) could perform 5,000 additions, 357 multiplications or 38 divisions. The use of vacuum tubes instead of switches and relays created the increase in speed, but it was not a quick machine to re-program. Programming changes would take the technician’s weeks, and the machine always required long hours of maintenance. As a side note, research on the ENIAC led to many improvements in the vacuum tube.
In 1948, Dr. John Von Neumann made several modifications to the ENIAC. The
ENIAC had performed arithmetic and transfer operations concurrently, which
caused programming difficulties. Von Neumann suggested that switches control
code selection so pluggable cable connections could remain fixed. He added a
converter code to enable serial operation.
In 1946, Eckert and Mauchly started the Eckert-Mauchly Computer Corporation. In 1949, their company launched the BINAC (BINary
Automatic) computer that used magnetic tape to store data.