|
A keyset or chorded keyboard (also called a chorded keyset, ''chord keyboard'' or ''chording keyboard'') is a computer input device that allows the user to enter characters or commands formed by pressing several keys together, like playing a "chord" on a piano. The large number of combinations available from a small number of keys allows text or commands to be entered with one hand, leaving the other hand free. A secondary advantage is that it can be built into a device (such as a pocket-sized computer or a bicycle handlebar) that is too small to contain a normal-sized keyboard. A chorded keyboard minus the board, typically designed to be used while held in the hand, is called a keyer. Douglas Engelbart introduced the chorded keyset as a computer interface in 1968 at what is often called "The Mother of All Demos". ==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. TipTap.mobi released a chording app for the iPhone based on Douglas Engelbart's design in 2010. 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「chorded keyboard」の詳細全文を読む スポンサード リンク
|