Why a UPC? Why do we need yet another computer form factor? Because handheld computers and PDAs, as good as they are, dont work for viewing long e-mails or documents. Theyre also poorly suited for developing or giving PowerPoint presentations, and lack the storage capacity to hold the critical documents we sometimes need while on the road. In short, they do about 80 percent of what we need a portable computer to do, and for most of us, that means we need our laptops as wellwhich makes the handheld redundant. The laptop, on the other hand, has all of the capacity and capability we need, but it is big and often not with us when we need it. So it has 100 percent of the capability but only comes with us around 70 percent of the time or less. Ultralight laptops have tried to fix this, but the displays and keyboards almost always seem a little too small for general use, and the devices are still too large to put in a pocket or purse.Changing usage patterns also point towards the UPC. Increasingly we are able to connect wirelessly, which means we can work from anywhere. And for many of us its more important to be able to read and comment on lots of e-mail than draft long documents while on the road.This is one of the reasons the handheld market has stalledeven in a connected world the handheld is simply too limited. However, I think there is still a substantial need for a small, fully functional device. Of course, what constitutes "fully functional" is a matter of debate. Jim says you cant use UPCs like a BlackBerry because they are too large, and you cant touch type because they are too small. But there are a lot of folks who dont touch type today, and there are even more who typically respond to an e-mail with a couple of sentences. Microsofts CEO is rather famous for responding to an e-mail in 10 words or less. For these folks a device like this could be ideal. Coupled with a larger keyboardeither a fold-up from a company like ThinkOutside or a wireless keyboard from Logitechan external mouse, and a large monitor at work and at home, this may be the ideal solution for many. Jim also argues that you cant watch DVDs on a UPC because it doesnt have a DVD drive. But with the recent settlement between Entrust and Microsoft, were that much closer to being able to put movieslegallyon the hard drive of a device like this. And if you can live with the limited library, you can even use a service like Movielink to do this today. Technology Enables This New Class Technology has been getting more compact as well. PCMCIA-sized drives now exceed 40GB. New x86 processors are efficient, draw little power and generate little heat. Single chip designs now squeeze in many functions that used to require dedicated processors. In addition, new small, very-high-resolution-screens from such companies as Toshiba allow a full Windows XP desktop to be shown on a 5-inch or 7-inch display. The colors are brilliant, and the resolution is high enough so that text can easily be read by the naked eye (at least for those of us who dont already need glasses). And dont think that this "downsizing" effort has reached its limit. Even smaller CompactFlash-sized drives from Hitachi and Toshiba have already reached 5GB and will continue to hold more data, and even get smaller in the future. Were also getting closer to a complete PC on a chip, and that will enable slimmer and smaller devices over time, too. Next page: Challenges to overcome.