Picture this: It’s portable. You write on it using a stylus. It’s about information, but also communications. It also plays an important role in education. Nope, it’s not a Tablet PC. It’s a wax tablet, what the Romans called the tabulae ceratera, and it’s over 2000 years old.

Perhaps we haven’t come that far after all.

The Romans probably didn’t invent the wax tablet. No, I’ll bet they stoled it from an earlier culture. But that’s because it was a handy thing to have.

Important documents may have been written on parchment, but drafts were probably taken on the wax tablet. It was used in messaging. Roman schoolboys used it for their homework. (Girls did not attend school.) And, no you didn’t do math on a wax tablet; math was done on the abacus — even square roots and cubes.

Fast forward 2,000 years.

The Tablet PC is a variation on the standard laptop computer concept. It has all the basic features of a laptop: light weight, battery power, wireless networking, but it features a screen that you can write on. Well, not really write on, but use a handheld stylus for digital input.

There are several variations on the basic tablet PC design.

Convertible. The most familiar tablet design, basically it’s a standard laptop with a swiveling lid. You can use it like a laptop with a full keyboard, or twist the screen around and fold it over flat to use the convertible in tablet PC mode.

Slate. A slate type of tablet computer lacks a keyboard completely. The thing merely features an LCD display on which you write. There may be other buttons around the screen, but there is no keyboard. I feel that eventually this type of design will take over the entire laptop PC market: think iPhone but with a much, much larger screen.

Hybrid. A hybrid tablet PC is basically a slate design with a detachable keyboard. This type of configuration is not very popular, though HP makes such a model. You might see more of these in the future.

I have a convertible tablet PC, a Thinkpad X61 (shown above). I confess that I don’t use it much (it’s actually in storage), and that’s because the thing is heavier than I’d like. But for taking quick notes, or folding up in a compact size for use on an airplane, the Thinkpad X61 is ideal.

For more information on tablet PCs as well as the current state of the Laptop computer, see my book Laptops for Dummies, 3rd Edition.