On a good keyboard you can do 10 chars/second.
On the hardware keyboard of the n900 you can do 3-4 chars/second.
With drawing (palm graffiti or swype) you can do 1-2 chars/second.

There are different possiblities to implement rythmic tapping.


I'm thinking of an on-screen system with 5 chars/second:
Like an old handy: 9 fields on the screen (3x3)
You use 3 fingers.
Only landscape orientation is possible (place for fingers)

Each field has different meanings following to the rythm.
In a unit of 3: The first letter is considered as consonant, the second letter is considered as a vowel and the third is again a consonant.
In a unit of 2: The first letter is a consonant and the second a vowel.
If you want a syllable beginning with a voyel you have to use a unit of 3 beginning with a "blank" letter.

For.each class of letters (vowels or consonants) you have two sets of letters, depending of the pressure.
This means 18 vowels and 18 consonants.
The vowels include diphtongs.
For the consonant a third pressure mode is necessary to have enough consonants.

You are tapping with the hardware keyboard open.
The thumb of the other hand uses the keybord for mode changes (special characters) and the space bar.

T9 will be useless on that speed. The user interaction disturbes rythm and thinking of the writer.

At least 5 chars/second are necessary to take lecture notes.


(Another good solution could be a good joystick or multi button mouse, together with the use of the hardware keyboard.
Perhaps it could be better to use a 4x3 field on the screen. This would allow all consonants with only to levels of pressure.)