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Sold at Auction: Vintage Hp-28s Hewlett Packard Calculator
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HP-28C/S
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Hewlett Packard HP 28S Advanced Scientific Calculator Tested & Working With Case | eBay
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HP-28S Advanced programmable Scientific Calculator | X1440.97 | Computer History Museum
HP 28s - Algebraic Entry - YouTube
Hewlett-Packard HP-28C Handheld Electronic Calculator | National Museum of American History
HP 28S - One of the early fully programmable calculators, circa 1988. : r/retrobattlestations
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HP-28C
