Brand

Used HP calculators

Hewlett-Packard made the calculators most people mean when they say RPN. Its 9100A desktop calculator of 1968 used it, and the HP-35 of 1972, the world's first handheld scientific calculator, brought the four-level stack of X, Y, Z and T to a pocket. The HP-65 of 1974 was the first programmable pocket calculator, and by 1977 the calculator division had moved from Cupertino to Corvallis, Oregon. The line here runs from the red-LED Woodstocks like the HP-25 and HP-29C, through the HP-41C of 1979, to the landscape Voyagers of 1981 and 1982 and the Pioneer, clamshell and HP 48 models of the late 80s and 90s. The HP 12C is HP's longest-running and best-selling product and is still made, now by licensees such as Moravia Consulting, which also brought out new Collector's Editions of the 15C and 16C. Collectors date the older HPs by their serial number: the first two digits plus 1960 give the year, and a letter gives the country, like A for the USA and S for Singapore.

23 calculators we cover.