History

The first PDA is considered to be the CASIO PF-3000 released in May 1983. GO Corp. was also pioneering in the field. The term was first used on January 7, 1992 by Apple Computer CEO John Sculley at the Consumer Electronics Show in Las Vegas, Nevada, referring to the Apple Newton. PDAs are sometimes referred to as "Palms", "Palm Pilot", or "Palm Tops".

Typical features

Currently, a typical PDA has a touch screen for entering data, a memory card slot for data storage and at least one of the following for connectivity: IrDA, Bluetooth and/or WiFi. However, many PDAs (typically those used primarily as telephones) may not have a touch screen, using softkeys, a directional pad and either the numeric keypad or a thumb keyboard for input.

Software typically required to be a PDA includes an appointment calendar, a to-do list, an address book for contacts and some sort of note program. Connected PDAs also typically include E-mail and Web support.

Touch screen

• Using a virtual keyboard, where a keyboard is shown on the touch screen. Input is done by tapping letters on the screen.
• Using external keyboard or chorded keyboard connected by USB, IR or Bluetooth.
• Using letter or word recognition, where letters or words are written on the touch screen, and then "translated" to letters in the currently activated text field. Despite rigorous research and development projects, end-users experience mixed results with this input method, with some finding it frustrating and inaccurate, while others are satisfied with the quality. Recognition and computation of handwritten horizontal and vertical formulas such as "1 + 2 =" was also under development.
• Stroke recognition (termed Graffiti by Palm). In this system a predefined set of strokes represents the various characters needed. The user learns to draw these strokes on the screen or in an input area. The strokes are often simplified character shapes to make them easier to remember.

PDAs for business use, including the BlackBerry and Treo, have full keyboards and scroll wheels or thumb wheels to facilitate data entry and navigation, in addition to supporting touch-screen input. There are also full-size foldable keyboards available that plug directly, or use wireless technology to interface with the PDA and allow for normal typing. BlackBerry has additional functionality, such as push-based email and applications.

Newer PDAs, such as the Apple iPhone and iPod touch include new user interfaces using other means of input. The iPhone and iPod touch uses a technology called Multi-touch.