John Willis, of the Varrier-Jones Foundation, spent Maundy Thursday in Cambridge investigating something for nothing.

Dasher is completely different. It is nothing like anything else I have seen. So what is it?

According to the company's website, 'Dasher' is an information-efficient text-entry interface, driven by natural continuous pointing gestures.

Dasher is a competitive text-entry system wherever a full-size keyboard cannot be used ­ for example, on a palmtop computer; on a wearable computer; when operating a computer one-handed, by joystick, touchscreen, trackball, or mouse; when operating a computer with zero hands (i.e. by eyetracker). We expect the eyetracking version of Dasher to be an especially big hit, as it allows the user to write text as fast as normal handwriting.

Dasher is fast, efficient, easy to learn, and fun to use. The simplest way of describing it is as a new way to type.

Imagine a square on the screen. On the right-hand side appear all the letters of the alphabet, each within its own coloured box. By moving the arrow on the screen towards the letters (upwards to 'a', downwards to 'z'), the letters within their coloured boxes move to the left. By running the arrow over the box containing a letter, that letter is chosen. The right-hand edge of the chosen box leads to a new set of letters. The program predicts the next likely letter and makes it easier to choose. By adding letters words can be typed.

Dasher has three really impressive aspects. The first (and probably the most important in the world of alternative technology) is that there are a number of options for the inputting device. The second is the predictive technology. The third is that it is free.

Maundy Thursday was a beautiful day this year so it was with a sense of disappointment that I went to spend the afternoon in the Cavendish Laboratory in Cambridge. I was not predisposed to be impressed.

David MacKay, Dasher's inventor, reader in Natural Philosophy, Department of Physics, Cambridge University, is a delightful egghead. He began with a simple demonstration.

MacKay used a stylus ­ a pen without ink for those like me ignorant of these things ­ to 'draw' across the screen of a small handheld personal organiser, a pocket Compaq. The letters appeared to dance to his tune, creating words, then sentences.

I was itching to try and it was as satisfying as it looked. I am lucky in that, although I have no hands, I can hold a stylus and I could control it sufficiently to write. My predisposition not to be impressed began to evaporate.

Next I was shown how Dasher could be operated by an eyetracker. David Ward, MacKay's student, who wrote most of the program, showed that it is possible to type 20 words a minute. An eyetracker requires calibration and considerable concentration. It is difficult to imagine many users who could use an eyetracker who would not be able to use a head mouse, which would be easier to use.

However, I was really impressed with the accuracy I managed to achieve, even in five minutes. The hardest part is trying to look at the letters you want to type next without directing the cursor to that point. But it is possible and the speed of typing is impressive.

As my preference is for a rollerball mouse, I asked the two Davids if they could set Dasher up with one. In no time at all one was connected and Dasher was responding to the movement of the rollerball. In fact this article has been written using Dasher with a rollerball mouse.

Dasher is so flexible that it is impossible to guess all the inputting techniques that will be used. I downloaded it at home the evening I first saw it and tried it out unsupervised. The speeds I reached in an hour surprised me. It is certainly much faster than single digit typing.

It may not be as quick as voice recognition, but it is more accurate, quieter and I believe easier to learn. It can only improve as input devices, in particular eyetrackers, improve.

For some, the movement of the letters and with it the increasing size of the squares, may be too taxing on the eye. I found it a little tiring after a while, but worth it for the typing speed I achieved.

The exciting thing about this truly different concept is the possibility of all sorts of other uses and I believe the real benefits of this program are yet to be thought of. The concept is so different that radical ideas could flow. Predictive technology has become part of the consumer conscience, with the growth of mobile phones and text messaging.

Dasher is based on four segments of text from English literature but it invites the user to scan in a training document. I chose one called The Varrier-Jones Foundation and was astonished when the letters flowed towards the arrow as if they knew they were the chosen ones.

Dasher is also designed to learn. So, the more you use it the better it predicts.

Another aspect that impressed me was the speed with which I could type. In only a couple of hours I was able to reach the same speed as typing with the equivalent of one finger.

David Ward, a real expert, as befits the writer of the program, claims he can reach about 30 words a minute. That seems quick but I believe a considerable number of users will achieve far faster speeds than with onscreen keyboards or other alternatives.

It is the predictive technology that creates the extra speed. As Dasher learns, the more it is used the faster it types. Adding training texts adds to the program's ability to predict more accurately and quicker. Of course it will not cater for all disabled computer users, but for those with only the use of one hand or less it really adds to the options available.

I did find one or two rough edges. When I saved my article to Notepad and copied it into Microsoft Word, I was left with a readable but ugly document. It required formatting that is not yet available through Dasher. It is also difficult to edit work once written.

Another shortcoming is the lack of numbers and full punctuation, but when I asked Mackay why there were no full stops, he responded by rewriting the program to include them.

It bears repeating that Dasher is free. Mackay is adamant that he did not want to patent Dasher. He just wants as many people to use it as can benefit from it, whether that means those who want to show off their handheld computers or those who need alternative technology to connect to their computer.

He would like to have the resources to keep Dasher free to download (www.inference.phy.cam.ac.uk/djw30/ dasher/download.html), but to achieve that he needs funding. If you can help, please contact him via the website.

I like Dasher and will use it. It has a lot of warts but it is in the process of development. It deserves to have the development funding that its inventor Mackay needs to keep it free. If you can, try it out, it¹s well worth a go.

Posted: May 9, 2002