In the beginning was the mainframe. In 1945 the U.S. government built ENIAC, an acronym for Electronic Numerical Integrator and Computer, to do ballistics trajectory calculations for the military; World War 2 was nearing its conclusion, however, so ENIAC’s first major job was to do calculations that undergirded the development of the hydrogen bomb. Six years later, J. Presper Eckert and John Mauchly, who led the development of ENIAC, launched UNIVAC, the Universal Automatic Computer, for broader...