The world’s first electronic digital computer, Electronic Numerical Integrator and Calculator (ENIAC) is first demonstrated at the Moore School of Electrical Engineering at the University of Pennsylvania, by John W. Mauchly and J. Presper Eckert. The ENIAC machine occupies a fifteen hundred square foot room. The ENIAC demonstrates that high-speed digital computing is possible using the vacuum tube technology available. Built of some 17,468 electronic vacuum tubes, ENIAC is in the largest single electronic apparatus in the world.