Tablet PCs have fallen far short of the industry's initial optimistic expectations. As we explored yesterday, four years after they were introduced, they still account for less than two percent of the laptops sold.

The reasons for this include their continuing high price (a substantial premium over conventional laptops) and the fact that touchscreens have not proved popular. Here are another six reasons why Tablets have been a flop so far.

3. Handwriting recognition software is not up to speed

"If you write with a page of chicken scrawl, it ain't going to work," said Gartner analyst Leslie Fiering.

The software that can be used to turn handwriting into text is not fully accurate, meaning that if your handwriting is sloppy, the text recognition will be poor, added Roger Kay, an analyst at Endpoint Technologies.

Microsoft's Vista operating system is supposed to help with autocompletion of handwritten words but will not help with poor handwriting, meaning that handwriting recognition will not be a key driver of the tablet PC technology, Fiering said. Doctors and salespeople who take notes with tablet PCs are basically interested in saving their handwritten notes for their own use later on, not converting them to text, she explained.

But even saving handwritten notes can be a problem, said Ken Dulaney, another Gartner analyst. He recounted a time when he tried to impress colleagues at a meeting by taking handwritten notes on a tablet and then sending them around quickly to everybody afterward. "What they said back was, 'Thanks Ken, but I can't read your handwriting. Next time, type your notes.' "

By contrast, officer Dana Brown, manager of technology initiatives at Altoona, Wisconsin's police department, said character recognition in the ThinkPad X41 Tablets has been "very good," when police officers have to write short descriptions on a form, perhaps one or two paragraphs.

"You have to train the software to recognise the handwriting," he noted. Primarily, having a tablet PC that takes handwriting input in the cramped police cruiser dashboard area means not having to provide added space for a keyboard. (The X41 is a convertible, which means the touch screen can be pivoted and placed on top of the keyboard, saving space over a fully opened laptop.)

4. Until Vista, tablet PC hardware needed a special operating system called Windows XP Tablet PC Edition.

Until Vista, users needed Windows XP Tablet PC Edition to use such functions as handwriting recognition and touch screen. This has meant that a user would face the annoyance of not being able to write in a password to start working, Fiering said. The user would have to type or tap in letters and symbols of the password first before getting to the handwriting capabilities. With the new Vista Business Edition, the tablet capability is integrated, and if the PC is enabled to take touch or pen input, the OS will recognise it, she said.

Vista will also improve navigation for tablet PCs, allowing flicks of the pen to scroll, go back, delete and undo, Fiering said. For example, a user can paste an item into a document or delete text with the flick of a pen. Because of these improvements with Vista, Fiering said, tablet PCs will improve somewhat in popularity.

5. Tablet PC form factors have improved, but still not enough.

Tablet PC screen sizes can only be so big or the machines will weigh too much for users to want to carry them, Dulaney noted. But having a larger screen is something many users want for greater space to take notes.

To keep the weight down, most tablets have 12-in. screens, and many models don't come with an optical drive as a result. None of the 12-in. models has a wide screen, Fiering said. Several manufacturers have introduced 14-in. screen tablet PCs, but they tend to be "heavy and unwieldy," and would limit a user's ability to carry the device to take notes as with a clipboard, Fiering said.

In earlier generations, mechanical problems were also evident, including problems with hinges on convertibles, Fiering said. Providing a latch that will work on the convertible models "still has defied all the hardware design engineers," she noted.

Many new second- and third-generation models are emerging, and Dell is planning a convertible model in midyear, said IDC analyst Richard Shim. Dell would not comment, but Shim said Dell's entry could dramatically improve sales of tablet PCs, if only because Dell has a reputation for its ability to flood the market with less expensive devices.

Dell's entry will also come about the time that miniature tablet PCs hit the market, including the 1 lb. OQO with a 5 in. touch screen. But both Shim and Fiering said ultramobile PCs, including tablet PC variants, will stay in their infancy for the next two years, partly because of high cost and relatively short battery life.

Hewlett-Packard, Lenovo, Toshiba and several other vendors offer tablet PCs, but "none are clear leaders and all are kind of running in last place," Shim said.

6. Tablet PC software for pen-enabled and touch applications has not been widespread, nor has it always been effective, until recently.

"The good news is that most key vertical industries and major ERP vendors now support tablet PC clients," Fiering said. Recently, more form application-creation tools have appeared. However, some typical PC applications, such as Adobe's Photoshop, don't fully integrate pen input, she noted.

7. Vendors of tablet PCs have largely failed to market the devices to consumers, focusing instead on vertical markets within the business segment.

"If vendors went after consumers, it would help" sales, Shim said. The value of touch screens, as an intuitive technology, needs to be marketed to consumers as well as mainstream business users, he said. Mini-notebooks, such as the OQO, could be marketed to consumers who are also business professionals, possibly expanding the consumer base for tablet PCs.

8. Perceptions that tablet PCs have not done well in the market make it harder to persuade buyers to try them.

"There's a negative stigma about tablet PCs now. People think that once they've failed, they are a failure forever, and that's not necessarily the case," Shim said. "It's true that they haven't lived up to expectations, but that's not everything."

Microsoft was asked why its tablet PC has not reached the mainstream as hoped for five years ago, but a representative did not answer directly. Instead, the representative issued the following statement via e-mail:

"As users seek the benefits of mobile computing, Microsoft is enhancing mobile features for all notebook PCs, and Tablet PC functionality plays a key role in this vision. In particular, the Tablet PC gives users the flexibility to use multiple forms of input to interact with their PC in more natural ways and get more things done from more places than ever before. As the Tablet PC platform continues to grow, Microsoft expects to see Tablet PC functionality on all Windows mobile PCs."

Meanwhile, plenty of success stories are starting to appear, and Fiering said she has seen growing interest. "Tablet PCs have followed the typical Gartner hype cycle around new technologies, which means they go through a frenzy when first introduced, then a trough of disillusionment" and, usually, a gradual upward climb, she said. "But they are still growing steadily."

Fiering said she used to hear of sales of tens of machines and then hundreds, such as nearly 500 Fujitsu LifeBook T4000 tablet PCs that are being used with campus Wi-Fi at St. Clare's Hospital in Weston, Wisconsin, to collect, share and store patient data. Today, Fiering said, she is hearing of tablet PC orders topping 5,000 machines.

Even with such optimism, Fiering admitted there's a nagging question whether the tablet PC can become mainstream, and she counsels her clients about it. "I actually talk large business accounts out of buying tablets across the board, but if there's a particular problem to be solved with a particular work group, they're fine," she said.