Volvelle
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A volvelle or wheel chart is a type of slide chart, a paper construction with rotating parts. It is considered an early example of a paper analog computer. Volvelles have been produced to accommodate
A 15th century volvella of the moon
A sixteenth-century wheel chart, a page of Astronomicum Caesareum by Petrus Apianus, 1540, apparently relating to the Moon. The red dragons mark out one odd-sized and 26 equal-sized central divisions; the orbital period of the moon is 27.3 days.
A volvelle from the sixteenth century edition of the De sphaera mundi by Johannes de Sacrobosco.
Code wheel
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A code wheel is a type of copy protection used on older computer games, often those published in the late 1980s and early 1990s. The wheels were sold with physical games, and upon starting the game or
Volvelle
…1985). Both volvelles served to impede copying of the games, because they contained information needed to play the game. Other games included similar code wheels. E6B…
A code wheel from the 1989 game Tunnels of Armageddon