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Photo of completed replica looking directly at the front
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Photo of completed replica looking directly at the front
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This drum holds 30 numbers of 50 bits each. (Two of the columns are spares).
They are operated on in parallel. It is the first use of the idea we now call "DRAM"
-- use of capacitors to store 0s and 1s, refreshing their state periodically.
It is the only surviving fragment of the original ABC built in 1939.
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Front view of frame with base two punch/reader near a door similar to 1939 photo
of original.
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Base two punch/reader viewed from front-center as operator would see it.
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View of base two punch/reader from left-rear.
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