The ENIAC computer is the first large-scale general-purpose electronic computer. Built at the University of Pennsylvania's Moore School of Electrical Engineering in 1946, ENIAC is an acronym for "Electronic Numerical Integrator and Computer," but its birth lay in World War II as a classified military project known only as Project PX. The ENIAC is important historically, because it laid the foundations for the modern electronic computing industry. More than any other machine, the ENIAC demonstrated that high-speed digital computing was possible using the then-available vacuum tube technology. ENIAC needs 220 tubes to calculate one decimal number, 8.800 tubes for 20 accumulators, for one whole calculation procedure it has 18.000 tubes ready. The whole machine takes 80 m2 of space.

A group of students at the Department of Electrical Engineering have designed "ENIAC-on-a-Chip. This was done as part of Eniac's 50th Anniversary Celebration. They have integrated the whole "ENIAC" on a 7.44 by 5.29 sq. mm chip using a 0.5 micrometer CMOS technology. Their goal was to recreate the original ENIAC, following its architecture and basic circuit building blocks as much as possible. Vacuum tube circuits were modelled with transistors. Mechanical switches were replaced with electronic ones, which are essentially transmission gates, decoder and memory elements. The ENIAC used a base 10 number system as opposed to base 2, not because the engineers were not aware of base 2 but that it was thought that it would require more vacuum tubes.


Source: http://world-information.org/wio/program/objects/993050976