Years ago, Microsoft proclaimed that the future of the notebook PC was the tablet PC. It was envisioned as a sleek slate designed exclusively for input with a digital stylus -- but customers demanded that they have keyboards like traditional notebooks.
So they changed it. The screen could swivel around and be folded back on top of the keyboard, resulting in a relatively fat tablet.
But tablet PCs were more expensive than their non-touch versions, and they were soon relegated to niche status, despite their usefulness.
Because tablet PCs need to have a touch-sensitive screen installed when they are produced, you haven't been able to add that function after you bought one.
Probably the product that came the closest thing to doing that was the IOGEAR Digital Scribe, which allowed you to control the cursor and "write" on the screen by moving a digital stylus around a piece of paper.
Hantech, though, has now released the SiSo Tablo which, in addition to working on a piece of paper, can be used directly on the PC's screen like a stylus. To do this, Tablo includes a USB device that looks like a miniature desk lamp that attaches to the top or sides of a PC screen. It tracks the movement of its stylus using ultrasound; the stylus requires three tiny batteries, each the size of an aspirin.
Tablo ships with Microsoft software that makes Windows think the PC is a tablet PC and allows all the tricks that a tablet PC can do, including handwriting recognition.
Tablo can be handy for creating a quick diagram, sketch, or signature inside a document. It could also be useful for filling out a large number of check boxes on digital forms. And because it works with so wide a variety of notebooks, Tablo offers you more choice in terms of PC configuration.
For example, Tablo can be used with inexpensive netbooks with 10-inch screens, whereas most tablet PCs have larger screens -- and the extra weight that comes with them.
But the overall experience of the device needs work. First, rather than simply clipping to the top of a laptop like a webcam, the Tablo receiver requires a tiny magnetic ingot that must be stuck to the laptop's surface and must be removed when the laptop is closed.
Also, even after calibrating the Tablo, the stylus wasn't as precise as that on a tablet PC. The stylus can feel unnerving against the screen. And, finally, since notebooks that aren't designed for a touch screen generally can't operate with their screen flat against a surface, a Tablo-equipped PC isn't as convenient for extended note-taking as a tablet PC.
A new generation of touch-screen notebooks will be made possible by the arrival of Windows 7. These will include support for touch technology that uses your fingers rather than a stylus (like an iPhone), and will support new enhancements that take advantage of touch.
While these will be more expensive than a cheap PC with Tablo, they will be able to do some slick things. Some will allow you to use both hands for natural manipulation of information -- for instance, expanding or shrinking a digital photo. If you must have pen input today, spend the extra money for a tablet PC. While the Tablo's price is tempting, sometimes a great touch interface is simply out of reach.