Anyone who follows the computer industry even remotely has heard the buzz about personal digital assistants, or PDAs. Few new electronic gadgets have enjoyed as much buildup as Apple Computer's Newton MessagePad and its competitors. But much of the attention hasn't been flattering. Most of it has focused criticism on one of the unusual features of the new devices--their ability to read handwriting. That debate has overshadowed other features that are more refined--and potentially more useful.

What, exactly, is a PDA? Basically, it's a handheld computer that acts as a pocket organizer and notepad. But unlike such organizers as Sharp's Wizard, it doesn't have a keyboard. Instead, you enter information by writing directly on the screen with a special pen. Built-in software turns your handwriting into typed text, and in some models, such as the Newton and the virtually identical Sharp Expert Pad, it even interprets what you've written. Say you jot down "dinner Tuesday with Ann." Newton converts your writing into text, then enters into its built-in calendar a 7 p.m. dinner appointment the following Tuesday with your friend. (It figures that's the hour you dine unless you tell it otherwise).

But that assumes the gadget understands what you've scribbled. That's a big if. Handwriting recognition in such a tiny device is an impressive technological achievement--a few years ago, only big, expensive computers could do it. But it's far from perfect. With Newton and the Expert Pad, both designed by Apple and manufactured by Sharp, you may end up with the wrong word entirely. The two other PDAs sampled, the Casio Z-7000 and AT&T's EO 440 make even worse mistakes, though the errors usually come up as wrong letters within a word.

Despite the iffy handwriting recognition, PDAs may appeal to salespeople, freelancers, and others with busy lives often spent on the road. These people may appreciate their sophisticated address books, to-do lists, and calendars. For those now relying on paper-based organizers, such as Filofaxes, PDAs can provide new functions, such as allowing users to search instantly for every reference to a George Smith they've ever jotted down or to locate quickly a long-lost appointment deep inside the calendar. But a laptop computer with the right software can do the same thing, and it offers a keyboard to boot for more reliable text entry.

FINGERTIP FAX. One of the PDAs, the EO, tries to do more than the others. The EO is much larger--about the length and width of a legal pad, compared with the videocassette size of the three others. That means its screen is bigger, making it more practical for composing letters. It's also the only PDA that offers a cellular- phone option. Not only can you make and receive phone calls on the road, you can send and receive faxes from the screen wirelessly. You can jot a quick message and fax it to someone without bothering to convert it into typed text. And when you receive a fax, you can mark it up with the pen and fax it back to the sender. That could be useful for editing or reviewing documents while traveling. In a test, the EO sent a fax from a speeding train.

These capabilities have prompted AT&T to dub its product a personal communicator instead of a PDA. The other models have more limited communications abilities.

The Newton/Sharp and Casio models promise the capability to receive--but not send--short text messages wirelessly via paging networks. But first, you must buy an extra-cost electronic card, available soon, that you insert into a slot in the PDA's side. The three also have a built-in infrared communication system that lets you wirelessly "beam" a message or other information to another PDA by holding the devices near each other. The PDAs must be of the same type, though: A Casio can't send to a Newton.

All the PDAs can be hooked up to a telephone wall jack as well, via an optional modem. That allows you to send and receive electronic-mail messages. The EO also can send and receive faxes over a phone line, while Newton can only send them. (Casio promises a fax-sending feature early next year.) All of the PDAs can be connected to a desktop PC via a cable to transfer information.

But there are some major differences between the three pocket-size PDAs. The Casio comes equipped with much more applications software, such as a special version of the Quicken personal-finance program. After keeping tabs of your expenditures while traveling, you can download the data into Quicken on your PC. In addition, the Casio (which also will be sold by Tandy and AST Research) contains software for America Online. So you can connect with that information and messaging service while on the road, provided you carry a pocket modem. Still, Newton and the Expert Pad have some advantages over the Casio. They're the only PDAs that recognize cursive as well as block letters, and they also have impressive sound effects. When you rub out a mistake, for example, you get a "poof" sound, and a puff of smoke appears on the screen.

The EO is the only true communications device among the four. But its extra features come at a price, in dollars, battery life, and portability. While the Newton/Expert Pad and Casio weigh about a pound, the EO, with its cellular-phone attachment, checks in at about three. The Newton and Expert Pad can operate up to two weeks on four AAA batteries, and Casio claims its PDA can last months on its three AA cells. But if you use the EO's cellular phone often, you can drain the juice from its rechargeable power pack in a matter of hours. (All of the models can be plugged into a wall outlet with an adapter.)

NOT FOOLPROOF. An EO, with cellular phone, sells for about $2,700. The Newton and Sharp run about $700 without options such as a modem. That's about the same price the Casio is expected to fetch; that model is just arriving in stores.

While prices and features vary, one thing all of the PDAs share is the handwriting-recognition problem. Of course, you can correct the errors, either by scratching them out and writing the words again or by pulling up a tiny representation of a keyboard on the screen and tapping on the keys with the pen. But even erasing an error isn't foolproof. Annoyingly, the machine often mistakes your scratch-out mark for a letter or word, giving you one more thing to fix.

With practice, you can learn to modify your writing so the machine can better understand it. And the Newton/Expert Pad twins even supposedly "learn" from their errors. But even after weeks of using a Newton, it still made too many mistakes for comfortable use. There is an option: With all the PDAs, you can turn off the recognition software and the device will store your notes in your own handwriting. But if you do that, you can't use the electronic search features.

So, should you succumb to the hype and buy a PDA? The answer may lie in your feelings about new technology and your temperament. In many ways, PDAs aren't ready for prime time. Like AT&T's VideoPhone, which is a technical marvel even though it produces a fuzzy, jerky picture, PDAs are more harbingers of the future than perfected products. If you get a kick out of owning the latest gadget, a PDA makes a great, albeit costly, conversation piece. It could also do some useful things, provided you have the patience to wrestle with it. But for most people, it would be best to wait for the next generation.

      Street price: About $700
      PROS: Recognizes cursive and block letters
      CONS: May misidentify 
      handwritten words if they aren't on its built-in list 
      AT&T'S EO 440
      Street price: About $2,700 with cellular phone
      PROS: Can fax
      CONS: Bigger, heavier, and more battery-guzzling; may misread written characters
      CASIO'S Z-7000
      Street price: About $700
      PROS: More built-in soft-ware, including Quicken and access to America Online
      CONS: May misread 
      handwritten characters
      Street price: About $700
      A virtual twin of the Newton (both are designed by 
      Apple and manufactured by Sharp), except for 
      slight cosmetic differences
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