Pen computing refers to computers that use a light pen or stylus instead of a keyboard and mouse for primary input. Common pen computers include personal digital assistants (PDAs), mobile devices such as cell phones, wireless tablet PCs and GPS receivers and other touch screen devices. The touch screen uses either gesture recognition or handwriting recognition to relay the item clicked or the information written on the screen to the computer.
Gesture recognition is used to identify input to carry out a command, while handwriting recognition is used to translate handwritten input into digital text. Users can write using normal characters or, in some cases, special recognizable characters. In some instances, the determination of whether a character is used as text or a command is based on where the character is input. For example, in one operating system, drawing a "B" could refer to the letter, bold facing text or toggling borders, depending on use and placement of the character.
While pen computing commonly refers to the movement of a stylus or pen directly on a computer’s touch screen, computers can also receive pen computing data from pen scanners and graphics tablets. A pen scanner is used by sliding a pen across printed text. The text is scanned into the computer and converted to usable text using optical character recognition (OCR) software. Another common pen-based system is a graphics tablet, typically used by graphic designers. In this configuration, the user draws with the pen on a tablet, or digitizer pad, and the input is converted to a digital drawing using graphics software.
Older pen computing systems used light pens that were aimed at cathode ray tube (CRT) monitors. This method, while very accurate, required the user to hold the pen up to the monitor and was uncomfortable for extended periods, causing muscle pain and fatigue. Light pen technology is still used in some industrial and retail environments that don’t require the user to hold the pen to the screen for extended periods of time.
Pen computing has evolved and become more user-friendly over the years. Some early devices were plagued by hard to learn proprietary symbols that were used to reference alpha-numeric characters and by faulty handwriting recognition software. Other devices were created with a narrow scope of available software, which kept them from being embraced by the mainstream public. Modern pen computing devices, like touch screen phones and GPS units, have become more widely used as they have developed practical applications and simpler, more effective user interfaces.