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Existing devices for communicating information to computers are either bulky, slow, or unreliable. Dasher is a data entry interface incorporating language modelling and driven by continuous two-dimensional gestures, e.g. a mouse, a stylus, or eye-tracker. Tests have shown that, after an hour of practice, novice users reach a writing speed of about 20 words per minute while taking dictation. Experienced users achieve writing speeds of about 34 words per minute, compared with typical ten-finger keyboard typing of 40-60 words per minute.

Although the interface is slower than a conventional keyboard, it is simple to use, and could be used on personal data assistants and by motion-impaired computer users. Dasher can readily be used to enter text from any alphabet.


Dasher project on Sourceforge SourceForge Logo


Desktop Dasher v2

Desktop Dasher v1

iPAQ Dasher

JDasher - a Japapese version of Dasher

Movies of Dasher in use

Dasher running on an Handheld

Dasher running on a Compaq iPAQ 3630: ipaq.mpg(8.8MB) ipaq.avi(90MB)
Dasher running on a Compaq iPAQ 3630: pocket.avi (3.9MB)

Dasher with an eye-tracker

Dasher with an eye-tracker: eye.mpg(5.7MB) eye.avi(54MB)

Dasher running on a PC

Standard codec

Should be viewable with any video player - Media Player (Windows), xanim (X11).


Techsmith TSCC codec

Compesses Dasher animations really well - I think its lossless too.

If you're running Windows, you might need the Techsmith TSCC codec for Windows.

Apparently, mplayer for Linux will play these animations too.


Animated gifs

Here is quite an old animated gif showing someone writing `hello_how_are_you'.



We have Dasher running on a Compaq iPAQ H3630 handheld: pocket.avi (3.9MB)

Dasher 2.0.3

Download Dasher for Pocket PC.

Here are some screenshots. The language model has been trained on a book.

Future plans

To make Dasher an integrated input method.
Make use of the built-in dictionary.

Write With Your Eyes

Dasher with an eye-tracker

AVI of Dasher with an eye-tracker: eye.avi (54MB)


We have an eyetracker from EyeTech Digital Systems. It consists of two infra-red emitters, and a camera which plugs into the back of a PC.


The eyetracker works under MS Windows and replaces the mouse pointer with a users gaze. Below is a photo of me using Dasher to write with my eye movement. I can write at about 50-100 characters per minute (10 - 20 wpm). With further development, faster speeds should be possible.

More on Eyetracking

See the Eyetracking Page for more details of our eyetracking system.

PPM language model

A PPM model is used in many text compression alogirthms. The one implemented here is order 5 and uses `escape method D'. It can compress most text to a little over 2 bits per character. A good reference for PPM is Witten Bell Cleary - Text Compression


In May 2000, we published a paper describing Dasher and the results of a user trial.

You can download the paper here. Some of the experimental results are below.


Each Dasher trial was 5 minutes long.

The keyboard experiment was for control purposes. Each trial was 2 minutes.


As of August 2002, the main download page for Dasher is here


Archive of all releases made by me during my PhD.

A summary on the features available in Dasher

Feature Dasher 1.6.5 Dasher 1.6.8
Re-sizable display x x
Configure font size x x
Japanese character set x  
Scandinavian character sets x x
Configure zoom-in rate x x

A note for Japanese users

The latest version of Dasher does not have support for the Japanese character sets. This is an issue which should be resolved when cygwin move to Tcl 8.3.

For the time being, please download dasher165.exe.

You will need to have some Japanses fonts installed.

Dasher in The Financial Times

February 2002

Discuss Dasher on Yahoo Groups

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Site last modified Mon Jun 9 15:01:44 BST 2003