Personal Digital Assistants

Personal digital assistants (PDAs) are small, hand-held computers. They use a form of touch screen technology, using a light pen or stylus as an input device rather than a keyboard. In addition, a detachable keyboard or a voice recorder can be used. PDAs are versatile information processing appliances. They are used frequently as personal information managers (PIMs) to recordtelephone numbers, addresses, appointments, and to-do lists. Also, PDAs can synchronize with microcomputers to transfer e-mail, text documents, spreadsheets, files, or databases. Other types of PDAs incorporate an integrated modem to connect with the Internet or to dial-up another computer in order to transfer data.

Some PDAs use wireless communications technology, providing great mobility. This use of wireless technology allows companies to provide PDAs to their employees in situations where laptops would be unworkable.

Palmtops, which are small computers that fit in the palm of one's hand, are also referred to as PDAs. The difference between a PDA and Palmtop computer is that the PDAs are pen-based, using a stylus rather than a keyboard for input, while the palmtop uses a small, integrated keyboard.

In 1993 Apple Computer introduced the first PDA, which was called the Newton MessagePad. Rather than just storing handwritten words, Newton converted them into typescript. Early versions of Newton had limited success with this difficult process. Three years later, 3Com's Palm Computing introduced the revolutionary PalmPilot. In June 1998, Microsoft began shipping a scaled down Windows operating system for manufacturers of palm-sized PCs. Apple's Newton was later taken off the market.

Several factors should be considered before purchasing a PDA, including what application software the user wishes to run; which types of input devices (keyboard, light pen, touch screen, voice recorder) are available and desired by the user; whether the amount of memory, specifically random access memory (RAM), and the life of the battery are sufficient for the user' needs; what size of the device is desired; and, of course, what price the user wants to pay. In 2001 prices for PDAs ranged from a low of $100 for a simple personal information manager to more than $1,000 for full-screen PDAs with integrated keyboards.

Other features available in PDAs are multimedia and audio capabilities, various screen sizes (starting with a full screen), and modems (integrated or not, wireless, or wired). Which features are most important depends on the tasks that the user wishes to perform. In addition to these standard features, mobile telephones or clip-on cameras can be combined with several PDA models.

Two of the leading manufacturers of PDAs are Palm, Inc. and Casio, Inc. PDAs made by Palm dominate the market with two popular models: the Palm m100 and the Palm VIIx. Both devices use the Palm OS 3.5 as an operating system, HotSync Manager 2.1.0, Pocket Mirror 2.0.7 as synchronizing software, and a 20-MHz Motorola DragonBall EZ as a processor. The Palm OS is fast, simple, and compatible with both Macintosh and Windows-based computers.

The amount of memory available in these devices is important, especially the amount of RAM. The Palm m100 has 2MB of RAM and 2MB of ROM. The Palm VIIx has more RAM (8MB) and the same amount of read only memory (ROM). Both use a touch screen as their input and havea speaker as well as an infrared port. To exchange data between Palm PDAs, users can beam information from one to another using an infrared port. Users also can place the Palm PDA into a docking cradle and synchronize their PDA with their microcomputers. The Palm VIIx has a docking serial cradle for synchronizing with a microcomputer and a built-in modem that can access the Internet or other networks without wires.

The PDA models produced by Casio offered the first 64-bit screens on the market. Casio's PDAs include the Casio Cassiopeia E-125 and the Cassiopeia EM-500. Both have color displays, use Windows CE 3.0 as an operating system and ActiveSync 3.1 as synchronizing software, and use a 150-MHz NEC VR4122 as a processor. Most of these use the Windows CE operating system (WinCE). WinCE is similar to Windows 95/98. It can run set-top TV controllers or small handheld devices that can communicate with each other and synchronize with Windows-based computers.

The Casio E-125 PDA has 32MB RAM while the EM-500 PDA has 16MB RAM. Both use touch screen or voice recorders as input and have a microphone and speaker as well as a stereo headphone jack and an infrared port.

PDAs must be trained to recognize their users' handwriting. To do this, the user must write each numeric digit and letter (in uppercase) several times on the screen with the light pen. Even so, recognition is not always 100 percent. For users who really want a keyboard, text can also be entered by tapping the light pen on the appropriate letters from an on-screen virtual keyboard. There are other problems with entering data on the screen with just a light pen. How can users delete an entire word, or bring up an entire document? These problems have been solved in several ingenious ways. For example, deletion of a word occurs by crossing it out on the screen. Tapping the light pen on the name of a stored document brings it up on the screen.

As these problems are being solved, new applications for PDAs are being developed and new technologies are being combined with PDAs. For example, Symbol Technologies, Inc. has combined PDAs with bar code scanning equipment. Symbol is supplying the Kmart Corporation with in-store wireless and mobile computing solutions in its entire chain of more than 2,100 stores. Kmart is using Symbol's wireless local area network (LAN) and the company's PDT 6840 wireless devices for receiving merchandise, tracking inventory, and printing labels, and on the sales floor for price checking and employee communications. Many market watchers believe that PDAs will gain wide use in a variety of business applications, especially retailing, warehousing, and inventory control.

Terri L. Lenox and Charles R. Woratschek

Microcomputers; Telecommunications; Wireless Technology; World Wide Web.

Brown, Bruce, and Marge Brown. "Expanding Possibilities." PC Magazine, March 6, 2001, pp. 188–200.

Turban, Efraim, R. Kelly Rainer, Jr., and Richard E. Potter. Introduction to Information Technology. New York: John Wiley and Sons, Inc., 2001.

Casio Corporation Web Site. <http://www.casio.com>

Products, Services & Company Information. Palm, Inc. <http://www.palm.com>

Symbol Technologies Web Site. <http://www.symbol.com>

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