Pen-based computing

Pen computing refers to a computer user-interface using a pen (or stylus) and tablet, rather than devices such as a keyboard, joysticks or a mouse.

Pen computing is also used to refer to the usage of mobile devices such as wireless tablet PCs, PDAs and GPS receivers. The term has been used to refer to the usage of any product allowing for mobile communication. An indication of such a device is a stylus or digital pen, generally used to press upon a graphics tablet or touchscreen, as opposed to using a more traditional interface such as a keyboard, keypad, mouse or touchpad.

Historically, pen computing (defined as a computer system employing a user-interface using a pointing device plus handwriting recognition as the primary means for interactive user input) predates the use of a mouse and graphical display by at least two decades, starting with the Stylator and RAND Tablet systems of the 1950s and early 1960s.

User interfaces for pen computing can be implemented in several ways. Actual systems generally employ a combination of these techniques.

The tablet and stylus are used as pointing devices, such as to replace a mouse. While a mouse is a relative pointing device (one uses the mouse to "push the cursor around" on a screen), a tablet is an absolute pointing device (one places the stylus where the cursor is to appear).

There are a number of human factors to be considered when actually substituting a stylus and tablet for a mouse. For example, it is much harder to target or tap the same exact position twice with a stylus, so "double-tap" operations with a stylus are harder to perform if the system is expecting "double-click" input from a mouse.

A finger can be used as the stylus on a touch-sensitive tablet surface, such as with a touchscreen.

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