Type

Used RPN programmable calculators

These are the HPs built for programs. The red-LED Woodstocks came first: the HP-25 of 1975 with 49 steps and the HP-29C of 1977 with 98 and Continuous Memory, then the 1979 HP-34C, the first pocket calculator with a root finder and numerical integration. The HP-41C arrived the same year with an alphanumeric display and four ports for memory, application pacs, a card reader, a printer and the HP-IL loop, and the 41CV and 41CX built more in. The LED models run on rechargeable packs that are usually dead by now and can be damaged by running on the charger alone, while the 41s run on N cells, so leaked batteries and broken contacts come first on every checklist.

6 calculators we cover.