NOTE: This page is out-of-date!
This is one of the extended analog computers I work with at Indiana University:
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Wires are attached to a grid of pins that perforate a sheet of semi-conductive foam:
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As the wires are attached, the voltage on the sheet fluctuates. This forms basis of analog computation. We manipulate the current on the wires to perform some calculation:
Click for a larger view.
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Underneath the foam sheet, the pins are attached to sensors, which may be read by a digital computer. We can read the voltage on each pin to extrapolate a graph of the voltage gradient on the sheet:
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The EAC pictured above has a built-in Ethernet controller, which allows us to read the sheet voltage remotely from a digital computer.
Bryce Himebaugh has developed a number of Perl scripts to communicate with the EAC. He also has a live demonstration of an EAC configured to compute the exclusive-or (XOR) of two values, the relevance of which is explained here.
My toolkit provides similiar functionality in a command-line interface:
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