The PC may not be dead yet, but Microsoft isn't wasting any time in developing a potential successor: Tablet PC. Tablet PC is the working title of a new concept from Microsoft -- and a pet project of chairman and chief technology officer Bill Gates -- that, according to sources, will be powered by processors from upstart chip maker Transmeta. The Tablet PC is a portable screen-based device, likely to be about the size of a legal-size pad of paper. In theory, the tablet will provide computing functionality similar to that of a notebook PC, but offer new features as well. It is likely the Tablet PC will also adopt a new voice user interface at some point. The Tablet PC has been under development in Microsoft Research for some time, but sources said Microsoft does not have device manufacturers signed up as of yet. However, Microsoft has, under the stewardship of vice president of technology development Dick Brass, created the updated Tablet PC prototype and is expected to bring a small number of Tablet PC samples to Comdex/Fall 2000 in Las Vegas later this month. During his Comdex/Fall keynote address, Gates will demonstrate the tablet and reiterate his vision on how consumers will use it and interact with it, Microsoft officials confirmed. But officials did not respond to requests for comment on further details of the tablet. A prototype of the tablet was first demonstrated at the unveiling of Microsoft's .Net strategy in June, when Gates showed off how a tablet would allow for handwritten input, such as note taking, alongside traditional keyboard input. Sources familiar with the project say that Microsoft is really in the early stages of designing the Tablet PC. The prototype expected to be shown by Gates, sources said, is a one-off design and Microsoft has only a small number of prototypes, probably fewer than 10. The device will likely be based on the embedded version of Microsoft's NT-kernel-based operating system, possibly some iteration of its forthcoming Whistler product. Tablet prototypes, sources said, have been built with Transmeta's low-power Crusoe processor. Sources confirm that Transmeta is working with Microsoft on projects, although officials of the chip maker could not comment on questions about a relationship, due to its coming initial public offering. Challenges ahead Microsoft will not be without challenges in bringing the device to market and making it successful. Notebook PC sales are growing quickly. Microsoft will have to essentially convince consumers to give up the notebook PC in favor of the Tablet PC. Microsoft is also hampered by user interfaces. The only interface that makes sense for the Tablet PC, besides a pen-input, is voice. Voice recognition for dictation, command, and control isn't to the level yet where Microsoft could rely on it as a user interface. Microsoft Research and a host of other companies are continuing to work on this problem; meanwhile, Microsoft has been integrating speech synthesis and recognition into a variety of forthcoming products, including Office 10, the next version of Office for Windows. One Microsoft competitor, Adobe Systems, which bought Microsoft eBook Reader competitor Glassbook this summer, is also working on its own tablet software, said Len Kawell, director of Adobe's eBook Development Group. While Kawell wouldn't offer details, he said Adobe has been showing off its tablet software to original equipment manufacturers and could be expected to have something close to shipping that it could show next year.