Page "HP-41C" Paragraph 1

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 ("< tt > ZERO DIVIDE </ tt >") instead of simply a blinking zero ; it could also specifically prompt the user for arguments ("< tt > ENTER RADIUS </ tt >") instead of just displaying a question mark.