I collect vintage calculators. Fascinated by the early pioneering digital technology and engineering that went into these things, as well as the unique appearance and construction techniques of an era where things were built to last.
Calculators with cool displays, like nixie tubes, VFDs, or panaplex displays? Sure, I have those, a plenty!

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Calculators with odd or unique features? I have scientific calculators that let you watch the numbers change live as it processes results. I have a calculator that can calculate infinitely large numbers by throwing away least significant digits, and having a rolling pattern of decimal shift indication, just add zeroes! I have an astrological calculator that calculates astrological alignments for the years 3000BC to 7000AD...
Why!

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Calculators with absolutely no chips... Just transistors, diodes and resistors? I got 'em!

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Memory stored as mechanical vibrations traveling down a coil of suspended wire? Check! Magnetostrictive delay lines store bits by applying a torsional twist to a wire with a transducer. Another transducer at the end of the wire picks up the bit stream of mechanical twists and amplifies the signal, injecting it back into the logic circuits. I've got several examples!

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Calculators that use CRTs and vectors to "draw" numbers. I have a couple of those too!

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Calculators also have keys... Ultimately, if it hadn't been for my calculators, I might not have ended up here!