Commodore US-1  
Written by Accutron on 2017-03-15  

The Commodore US-1 is a compact four-function desktop calculator with some unusual technology and features. The US-1 is based on the General Instrument C-500 single-chip calculator, an obscure device that was only used in a handful of machines. Unlike other similar calculators, the constant on the US-1 works with all four functions, instead of only working with multiplication and division. The US-1 also has a particularly odd divide-by-zero behavior, in which the least and third least significant digits count upward.


Commodore US-1 four-function desktop calculator.


US-1, internal construction. Note the General Instrument C-500 single-chip calculator and eight-digit Panaplex style display.

This article is part of the [Electronic Calculators] exhibit.

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