Everyone can do something nobody else can: read their own handwriting. This task requires a tremendous amount of processing power and often specialist knowledge.
Sometimes I can only read my notes if I can remember what the meeting was about and roughly what was said. Expecting a computer to do it requires an astonishing faith in technological progress, or writing in ways it can understand. For example, if you want a handheld device to recognise a K instantly, you write it as a Greek alpha.
For more than a century, the solution has been obvious. It is called a keyboard. An invaluable skill called "touch typing", which can be learnt in a couple of hours with KAZ software, enables people to type at 80-120 words a minute. This is much faster than they can write, and faster than many people can think.
But typing is not always practical, or socially acceptable, or the best way to do something. It's hard to type standing up on a bus. Typing in meetings is frowned upon. And puzzling out ideas often means putting words in boxes, linking them with arrows, then adding stick figures or clouds. The ideal medium is the back of an envelope.
This is what Microsoft's Bill Gates wants to computerise next, to judge from his keynote speech at last month's Comdex. He showed a Tablet PC that you can use for typing (with a detached keyboard) then pick up and take to a meeting for use as a pen-operated wireless device.
As demonstrated, the Tablet recognises "ordinary" handwriting and lets you treat it the same as word processed text. Link a couple of ideas with an arrow and the arrow is preserved even if more text is inserted between the words. No envelope can actually do that.
The problem is that what the Tablet is doing is much harder than it looks, as Apple found out when its Newton handheld computer flopped. This was a far less ambitious design, but users were still disappointed by its inability to do what they expected.
If Microsoft can meet those expectations by 2002, I'll be gobsmacked.
On the other hand, success is now much more important than most people realise. Keyboards are great for typing English but much less useful for Chinese, Japanese, Korean and other languages used by billions of people.
If Tablet PCs work as promised, this will be cute in Seattle and Silicon Valley but devastatingly important in Tokyo, Seoul and Beijing.
Jack Schofield is computer editor of The Guardian