Subject areaArtificial intelligence
Also known asOdhner arithmometerpin-wheel calculator
A pinwheel calculator is a mechanical calculator that sets each digit by pushing zero to nine pins out of a disc.
Turning the crank, the protruding pins act as teeth and advance the matching digit in the result register. According to John Wolff, all machines of this type derive, to a greater or lesser extent, from the designs of Willgodt Theophil Odhner in the 1870s and 1880s, which is why it is also called the Odhner arithmometer.
It works in four parts:
- setting: each digit has a ring with a small lever; turning it, a ramp pushes the disc's pins out or pulls them back;
- addition and carry: at every turn the pins advance the number wheels, and when a wheel passes from nine to zero the tens carry moves to the next wheel, in a cascade;
- the counter: it counts the crank turns, which is how the multiplier of a multiplication or the quotient of a division is read;
- subtraction: the crank is turned the other way.
Compared with the Leibniz stepped drum, the system of earlier machines, the pinwheel takes far less space, and that explains its success in offices. It is one of the most widespread technologies of intelligence before the computer: it gave rise to the Original-Odhner and Brunsviga families, the latter developed in Germany by Franz Trinks.
Source: John Wolff, Original-Odhner Technical Description, per il meccanismo e la derivazione dai progetti di W. T. Odhner degli anni 1870-1880; Wikidata Q2861432.
An example
The case below is constructed, because the term does not yet appear in the articles. In the accounts office of a 1930s chemical company, a clerk sets the amount of an invoice with the levers, then turns the crank three times: the register shows three times the amount, and the counter confirms three turns.
Enrico Giubertoni. Licensed under CC BY-NC 4.0: you may quote, translate and adapt this entry with the author’s name and a link, stating any changes. For commercial use, write to info@enricogiubertoni.com
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