Pen computing


Pen computing refers to any computer user-interface using a pen or stylus and tablet, over input devices such as a keyboard or a mouse.
Pen computing is also used to refer to the usage of mobile devices such as tablet computers, 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 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.

General techniques

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

Pointing/locator input

The tablet and stylus are used as pointing devices, such as to replace a mouse. While a mouse is a relative pointing device, a tablet is an absolute pointing device.
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.

Handwriting recognition

The tablet and stylus can be used to replace a keyboard, or both a mouse and a keyboard, by using the tablet and stylus in two modes:
Different systems switch between the modes by different means, e.g.
The term "on-line handwriting recognition" is used to distinguish recognition of handwriting using a real-time digitizing tablet for input, as contrasted to "off-line handwriting recognition", which is optical character recognition of static handwritten symbols from paper.

Direct manipulation

The stylus is used to touch, press, and drag on simulated objects directly. The Wang Freestyle system is one example. Freestyle worked entirely by direct manipulation, with the addition of electronic "ink" for adding handwritten notes.

Gesture recognition

This is the technique of recognizing certain special shapes not as handwriting input, but as an indicator of a special command.
For example, a "pig-tail" shape would indicate a "delete" operation. Depending on the implementation, what is deleted might be the object or text where the mark was made, or the stylus can be used as a pointing device to select what it is that should be deleted. With Apple's Newton OS, text could be deleted by scratching in a zig-zag pattern over it.
Recent systems have used digitizers which can recognize more than one "stylus" at a time, and make use of Multi-touch gestures.
The PenPoint OS was a special operating system which incorporated gesture recognition and handwriting input at all levels of the operating system. Prior systems which employed gesture recognition only did so within special applications, such as CAD/CAM applications or text processing.

History

Pen computing has very deep historical roots.
For example, the first patent for an electronic device used for handwriting, the telautograph, was granted in 1888.
What is probably the first patent for a system that recognized handwritten characters by analyzing the handwriting motion was granted in 1915.
Around 1954 Douglas T Ross, working on the Whirlwind computer at MIT, wrote the "first hand-drawn graphics input program to a computer".
The first publicly demonstrated system using a tablet and handwriting text recognition instead of a keyboard for working with a modern digital computer dates to 1956.
In addition to many academic and research systems, there were several companies with commercial products in the 1980s: Pencept, Communications Intelligence Corporation, and Linus
were among the best known of a crowded field. Later, GO Corp. brought out the PenPoint OS operating system for a tablet PC product: one of the patents from GO corporation was the subject of recent infringement lawsuit concerning the Tablet PC operating system.
The following timeline list gives some of the highlights of this history: