Among the eight zillion products here at the Consumer Electronics Show (CES) in Las Vegas are some new iterations of the ultramobile PC (UMPC), devices the size of a paperback book that have touchscreens and run Windows Vista.

I didn't see 'em all, but I did check out Toshiba's technology preview of a UMPC it's working on. What Toshiba is showing is an early rough draft; the company won't say when the device might go on sale, and the demo shows one being powered by a fuel cell, something that's not going to happen any time in the short-term future.

The Toshiba UMPC packs a number of advanced input technologies, including motion sensors that let you scroll around by tilting the entire device around. The company is working on unique finishes that could make it better-looking than any UMPC before it. All in all, it's an impressive piece of next-generation technology.

And yet it looks like it'll be just as crippled as all its predecessors, because the whole UMPC concept is based on a fundamentally bad idea: putting a full-blown copy of Windows on a device with an undersized screen and no keyboard.

The Windows Vista user interface was designed to make sense on PCs with large displays and lots of pixels. On the Toshiba, text is barely legible, and the icons in the System Tray were so small I couldn't figure out what they were, period.

Like other UMPC companies, Toshiba has incorporated workarounds to deal with this, like a mode that magnifies part of the screen so you can actually read URLs as you input them into Internet Explorer. But that's inherently kludgy - shouldn't the default type size on a portable computing device be large enough to read?

The situation is similar with input. The Toshiba has the aforementioned motion sensors, several buttons for performing mouse-like manoeuvres, a mode that puts a virtual touchpad on the screen, and an onscreen keyboard that's broken into sections on each side of the screen.

Most of which merely compensate for the fact that Windows Vista is designed to use a mouse and full qwerty keyboard - items which UMPCs don't have room for. I've never seen a UMPC which rethought how you interact with a small computer from the ground up, rather than trying to work around Windows' deskbound origins.

As I got a demo of Toshiba's prototype, it dawned on me that one company has managed to make an UMPC that leapfrogs past all the ungainliness of all the other ones on that market.

NEXT PAGE: the iPhone. Now that's what I call mobile computing > >

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Among the eight zillion products here at the Consumer Electronics Show (CES) in Las Vegas are some new iterations of the ultramobile PC (UMPC), devices the size of a paperback book that have touchscreens and run Windows Vista.

No, I'm not talking about OQO or FlipStart - I'm thinking of Apple and the iPhone. The iPhone is pocket-sized, which makes it infinitely more portable than the not-quite-pocket-sized UMPCs out there. The multitouch user interface is different from and better than the pseduomouse features on UMPCs. The iPhone's menus make everything legible. The onscreen keyboard is far from perfect, but I haven't seen a UMPC that does qwerty better.

Of course, UMPC supporters might bring up one seeming point in that platform's favour compared to the iPhone: UMPCs run full Vista and can therefore run just about any Windows application, while the iPhone's simplified version of OS X isn't compatible with Mac apps, and Apple is only now getting around to letting third-party developers write iPhone programs at all.

But it seems to me that the manifold compromises and limitations of the UMPC largely negate the value of full Windows compatibility. UMPCs can run a lot of software, but it can't run it very well at all.

That's why I'm not optimistic about the future of the UMPC platform-but am intrigued by the upcoming Windows Mobile 7.0, which, if this post at InsideMicrosoft has its facts straight, will go a lot further towards rethinking Windows for small devices. And I suspect that both the iPhone and Windows Mobile will flourish long after the UMPC quietly vanishes from the market...