During the World War, the U.S military had a demand for fast computers that could perform extremely complex calculations and weather predictions in minutes. This was when the ENIAC was built, by a partnership between University of Pennsylvannia and the U.S government. After the landmark "Von Neumann Architecture" was introduced it considerably increased the speed of the computer since it used only one memory. The EDVAC and UNIVAC were built based on this architecture using vacuum tubes. All the computers built from 1941-1956 are called 'first generation computers'.