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The Digi-Comp I was a functioning, mechanical plastic toy computer sold in kit form. It was manufactured by E.S.R. Inc. starting in 1963. With a three-digit readout, it could be programmed to demonstrate binary logic and perform various operations such as addition, subtraction and multiplication. Many people remember owning a Digi-Comp I in their childhood and they often fetch prices of $150 or more on eBay. They originally sold for $6.00.