Principles of Operation
Each key is mapped to a number and then can be mapped to a corresponding letter or command. By pressing two or more keys together the user can generate many combinations. In Engelbart's original mapping, he used five keys: 1,2,4,8,16. The keys were mapped as follows: a = 1, b = 2, c = 3, d = 4, and so on. If the user pressed keys 1 + 2 = 3 simultaneously the letter "c" appeared. Since Engelbart introduced the keyset, several different designs have been developed based on similar concepts.
As a crude example, each finger might control one key which corresponds to one bit in a byte, so that using seven keys and seven fingers, one could enter any character in the ASCII set—if the user could remember the binary codes. Due to the small number of keys required, chording is easily adapted from a desktop to mobile environment.
Practical devices generally use simpler chords for common characters (e.g., Baudot), or may have ways to make it easier to remember the chords (e.g., Microwriter), but the same principles apply. These portable devices first became popular with the wearable computer movement in the 1980s.
Douglas Engelbart recently filed two new patents for mobile chorded keyset devices and TipTap.mobi has released a chorded app for the iPhone with Douglas Engelbart.
Thad Starner from Georgia Institute of Technology and others published numerous studies showing that two handed chorded text entry was faster and yielded fewer errors than on a QWERTY keyboard. Currently stenotype machines hold the record for fastest word entry. Many stenotype users can reach 300 words per minute. However, stenographers typically train for three years before reaching professional levels of speed and accuracy.
Read more about this topic: Chorded Keyboard
Famous quotes containing the words principles of, principles and/or operation:
“... the history of the race, from infancy through its stages of barbarism, heathenism, civilization, and Christianity, is a process of suffering, as the lower principles of humanity are gradually subjected to the higher.”
—Catherine E. Beecher (1800–1878)
“Though the ancients were ignorant of the principles of Christianity there were in them the germs of its spirit.”
—Herman Melville (1819–1891)
“You may read any quantity of books, and you may almost as ignorant as you were at starting, if you don’t have, at the back of your minds, the change for words in definite images which can only be acquired through the operation of your observing faculties on the phenomena of nature.”
—Thomas Henry Huxley (1825–95)