The Maniac III was a second-generation electronic computer (i.e., using solid state electronics rather than vacuum tubes), built in 1961 for use at the Institute for Computer Research at the University of Chicago

University of Chicago

The University of Chicago is a private research university in Chicago, Illinois, USA. It was founded by the American Baptist Education Society with a donation from oil magnate and philanthropist John D. Rockefeller and incorporated in 1890...

.

It was designed by Nicholas Metropolis

Nicholas Metropolis

Nicholas Constantine Metropolis was a Greek American physicist.-Work:Metropolis received his B.Sc. and Ph.D. degrees in physics at the University of Chicago...

 and constructed by the staff of the Institute for Computer Research. Its design was changed to eliminate vacuum tubes, and thus it occupied a very small part of a very large and powerfully air-conditioned room. It used 20,000 diodes and 12,000 transistors, and had 16K 48-bit words of core memory. Its floating multiply time was 71 microseconds, and divide was 81 microseconds.

Its most novel feature was unnormalized significance arithmetic

Significance arithmetic

Significance arithmetic is a set of rules for approximating the propagation of uncertainty in scientific or statistical calculations. These rules can be used to find the appropriate number of significant figures to use to represent the result of a calculation...

floating point. This allowed users to determine the change in precision of results due to the nature of the computation.