Microsoft's recent push to promote the so-called Tablet Edition of Windows XP was supported by a number of notebook manufacturers, including Toshiba, which unveiled its Portégé 3500 Tablet PC.

There are two varieties of Tablet PC; those which are entirely dependent on pen input and those with a keyboard like a conventional notebook. The Portégé 3500 is of the second type, in fact it bears a very close resemblance to the Portégé 2000 on which it is clearly based.

Some see this as a strength, others as the first problem. On the positive side, the fact that the Portégé is a 'convertible' means that you have full conventional notebook functionality cleverly paired with pen input. On the negative, the 3500 is significantly more expensive than a comparably specified no-pen alternative. You are clearly expected to pay a premium for Tablet technology.

So what exactly do you get that's different? Well, the short answer in hardware terms is not actually all that much.

Everything hinges, if you'll pardon the pun, on the way the lid is attached. You can open it up and work on the keyboard as per a normal clamshell notebook, or you can pivot the screen around 180 degrees until it faces away from you, then close the lid. Now you have a tablet, writing surface uppermost, ready for pen input.

An icon on the Taskbar lets you walk the screen orientation round in 90 degree steps, giving you the choice of two portrait and two landscape display alignments. You will probably find yourself making use of this feature even if you simply want the default landscape view you get by rotating and closing the lid.

When you first do this, the image on the screen is upside-down, so you turn the notebook-now-tablet around. It's then that you realise that the machine itself is wedge-shaped in profile, because now the screen tilts away from you.

This is bad for the viewing angle, never mind the ergonomics of actually writing, so you need to flip the image around 180 degrees rather than the notebook in order to get everything the way it should be. By this time, you might be getting just a little frustrated, and the software controlling the screen orientation doesn't let you store your preferred settings, so you have to repeat the process every time.

If you need to carry the Portégé around as you work, which seems likely given the natural synergy between pen input and vertical markets from stock control to medicine, you may start to tire of it after a while. On the face of it, the 1.85kg it weighs doesn't seem much, but try carrying it around in the crook of your arm for several hours and see if it feels as light as when you started.

The machine would have been heavier if it had either a floppy or an optical drive, but it has neither. Both are options (£59 and £165 for a floppy and a CD-ROM respectively), and both must be connected externally.

This drew our attention to the fact that the Portégé is light on ports. You get two USB, VGA and a combo modem/LAN jack, and that's the lot. Apparently a USB port replicator is in the pipeline, but for now you have to make do with what you get.

When it comes to actually using the pen interface, the results are mixed. On the one hand you have to admire the way the handwriting recognition can handle cursive script written at any angle, on the other you curse its insistent misinterpretations of a carefully re-written word. Like all handwriting recognition software, the XP Tablet extensions are imperfect, though still impressive on occasion.

On the hardware side, the way the pen activates the cursor before the nib actually touches the screen takes some adapting to - although this is written into Microsoft's Tablet PC specification, so it's a feature not a bug. Also, the hard, slippery surface of the screen makes neat, consistent handwriting hard to achieve.

The relatively modest 12.1-inch screen is coupled with a native resolution of 1024 x 768. This makes everything fairly small and harder to hit accurately with that rather lively cursor, which tends to start moving just before you expect it to. That said, custom applications designed for tasks like data collection will almost certainly work well on the Tablet PC platform, which means that where there's a need, there should be a market for the concept.

On batteries the Portégé runs for around 2.5 hours, which is important since this is a machine designed to be used on the go. With this in mind we can live with the figure, although something closer to 3.5 hours would have been much better.

The machine is based on a 1.33GHz Pentium III-M backed up by 256MB of PC133 SDRAM and a 5,400 rpm 40GB IBM TravelStar hard disk. Graphics get the treatment from a basic Trident CyberAladdin-T GPU which grabs 16MB of memory from the main system for its own use.

The result is solid, middle-of-the-road performance which will answer the needs of the typical Tablet PC user wanting to run Windows applications with some degree of pen input and customisation.

When you step back from the Portégé, it's overall high standard of build and essentially quite clever design (screen orientation niggles aside) are clearly evident. Ponder a while longer and the relative lack of ports and the absence of either a floppy or optical drive may begin to rankle, especially if you are already gritting your teeth at the premium you are paying for Tablet technology.

It really remains to be seen how strong the demand will be for convertible Tablet PCs like this. Plain, pen-only Tablet PCs are lighter to carry and cheaper to buy, so each approach has its advantages, and will probably find its own market. While there will certainly be a demand for the Tablet PC concept, it is safe to say that the world will not be converting wholesale overnight, whatever Microsoft might have us think.

Toshiba has essentially got it right with its 'convertible' design, and there's no doubt that the Portégé 3500 is a quality product. It's also relatively expensive, especially when you consider that the floppy and optical drives are charged as extras. A good start to the Table PC era, but there's still work to be done.