0kelseymh 12 years ago http://www.google.com/search?hl=en&q=how+do+punch+card+readers+work&btnG=Google+Search&aq=f&oq=Search result #9, paragraph 6, "Electric wires in the card reader made contact with mercury in a cup through holes in the cards to complete an electric circuit and "read" the data."
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12 years ago
http://www.google.com/search?hl=en&q=how+do+punch+card+readers+work&btnG=Google+Search&aq=f&oq=
Search result #9, paragraph 6, "Electric wires in the card reader made contact with mercury in a cup through holes in the cards to complete an electric circuit and "read" the data."