PDAs.(personal digital assistants )(Buyers guide)

Besides serving as an address book, calendar, and to-do list, many personal digital assistants offer multimedia functions.

PDAs can store thousands of phone numbers, appointments, tasks, and notes. All models can exchange, or synchronize, information with a full-sized computer. To do this, you connect the PDA to your computer via a cradle or cable. For models that run on rechargeable batteries, the cradle doubles as a charger. Infrared, Bluetooth, and Wi-Fi (wireless) let you synchronize with a computer without wires or a cradle.

Most PDAs can be made to work with both Windows and Macintosh computers, but PDAs with the Pocket PC operating system usually require third-party software for Macs. PDAs with Wi-Fi (wireless) capability can access the Internet. Those without can with the addition of a separately purchased modem. Most PDAs can record your voice, play videos, display digital photos, and hold maps, city guides, and books.

WHAT'S AVAILABLE

Most PDAs on the market are the familiar tablet-with-stylus type that feature a squarish display screen, a design pioneered by Palm Inc. Today the main choices are models that use the Palm operating system (OS)--mostly Palm models--and Pocket PC devices from companies like Dell and Hewlett-Packard. The latter use a stripped-down version of Microsoft Windows. A few PDAs use a proprietary operating system. Hewlett-Packard, Nokia, Palm, Samsung, and Sony Ericsson offer units that combine a cell phone and a PDA, often referred to as smartphones.

Palm OS systems. Equipped with software to link with Windows and (for Palm-brand units) Macintosh computers, Palm units and their clones have a simple user interface. You use a stylus to enter data by tapping an onscreen keyboard or writing in shorthand known as Graffiti. Some models have a tiny tactile keyboard. Or you can download data from your computer.

Most Palm OS-based PDAs can synchronize with a variety of desktop e-mail programs, such as Outlook Express and Eudora. (Palm models with VersaMail software are good at handling e-mail with attachments.) And all include a basic personal information management (PIM) application. Palm OS units are easy to use, although navigation between different programs is cumbersome because of the operating system's "single tasking" nature.