High Quality Content by WIKIPEDIA articles! The HP-41C series are programmable, expandable, handheld RPN calculators made by Hewlett-Packard from 1979 to 1990. The original model, HP-41C, was the first of its kind to offer alphanumeric display capabilities. Later came the HP-41CV and HP-41CX, offering more memory and functionality. The alphanumeric LCD screen of the HP-41C revolutionized the way a calculator could be used, providing user friendliness (for its time) and expandability (keyboard-unassigned functions could be spelled out alphabetically). By using an alphanumeric display, the calculator could tell the user what was going on: it could display meaningful error messages ("ZERO DIVIDE") instead of simply a blinking zero; it could also specifically prompt the user for arguments ("ENTER RADIUS") instead of just displaying a question mark.