Desktop or, more often, portable electronic devices that are used to perform arithmetic, statistical, or other, more complex processing operations at the step-by-step direction of the user or by execution of a program (a stored sequence of processing operations) selected and initiated by the user. Models are offered with particular stored programs specialized to professional fields such as finance and science, and results are displayed in formats ranging from the still prevalent single line of alphanumeric characters to small viewing screens capable of graphical representations.