Now let's look in more detail at the hardware additions that turn the TM-100 into a Tablet PC. The rotatable screen is the heart of the convertible. To convert to tablet mode, you (1) push in on the screen latch and open the screen to between 85 and 95 degrees, (2) push to open the spring-loaded latches on each side of the screen, (3) rotate the screen 180 degrees clockwise (only), (4) push to close the latches on each side of the screen, (5) close the screen face-up over the keyboard, and (6) slide the screen latch to the "tablet position" to secure the screen to the body. This sounds like a long process, but after you practice it a few times, it only takes about seven seconds.

On the pre-production TM-100 that I was given to review, the rotatable hinge has some free play that makes it feel less than totally durable. In the open-and-close direction, the hinge feels just as solid as any other notebook hinge. But because the screen is supported on a single hinge in the center of the product rather than the usual pair of hinges, there's about 0.1" to 0.2" of free play (depending on the screen position) in the side-to-side rotation direction. Acer says they've done extensive robot testing of the hinge mechanism for up to 30,000 cycles, well beyond their standard hinge spec of 18,000 cycles. Rotating the screen 24 times per day, five days per week, 50 weeks per year for three years adds up to 18,000-more than even the heaviest user will experience in the typical three-year life of a notebook.

The electromagnetic digitizer in the TM-100 is made by Wacom. The primary characteristic of all electromagnetic digitizers is the ability to "hover," or move the cursor without actually touching the screen. The TM-100 comes with two battery-less electronic pens. The first is a PDA-size (0.22-inch diameter) "emergency" pen that is housed in the edge of the screen bezel. The second is a "regular-size" (0.35-inch diameter) pen that does not have a permanent storage location. Both pens have barrel (side) buttons; the default function of the button is right-click (the pen tip is left-click). The regular pen also has an "eraser" (a second electronic sensor) in the top of the pen. The feeling of the pen on the screen is much too slippery - it's like writing on ice, not at all like writing with a ballpoint pen on paper. Acer says they're going to work on adjusting the feel to give more writing resistance.

There are five buttons on the lower right corner of the screen bezel. The first button is dedicated to CTRL-ALT-DEL. This is required for security because it might be possible to spoof (hack) the on-screen keyboard, but it's impossible to spoof a hardware button. The second button is a "Function" button that allows modifying the action of the three remaining buttons. The default functions of the three remaining buttons are Up, Down and Enter. The default modified functions are Rotate Screen, Esc and Tab. Each of the three programmable buttons can be set to any of 23 different functions, ranging from controlling speaker volume to launching an application to playing back a recorded sequence of keystrokes. The buttons can even be assigned different functions based on the screen orientation. This functionality is so handy that you quickly find yourself using the buttons even when you're in notebook mode.

From a purely hardware perspective, this is a fine little notebook. If your mobile computing needs fall into the ultraportable notebook class, this will definitely be a product worthy of serious consideration. When you add in the Tablet PC capabilities that give you a whole new way of working with your PC, it becomes even more attractive. - -Geoff Walker