Unlike the Persistent Architecture of the standard-issue desktop keyboard, a chorded keyboard is an input device that allows a user to type in a chordal pattern. The advantages of chordal keyboards are that they allow their users to type with one hand, or while moving around. The Twiddler chorded keyboard is perhaps the most popular chorded keyboard in existence. It has been used by Steve Mann, Thad Starner and their respective students.
Various students at MIT and Carnegie Mellon University have used the Twiddler as the primary input device for class notes, everyday writing such as E-mail and even entire dissertations. When starting the MIT Wearable Computing Project, Georgia Tech and former MIT Media Lab professor Thad Starner issued every member a Twiddler as their primary text input device.  Twiddler was one of the first components Thad Starner bought when designing his wearable computer. Over time, the Twiddler and his wearable computer replaced his desktop computer. All of Starner's writing, including his PhD thesis, was written with the Twiddler.
Thad Starner and others produced a research study on the various rates of one handed mobile input with the Twiddler and reported that some test subjects could achieve speeds of up to 60 wpm on the devices.. Starner found that many new users were up to 10 words a minute with a weekend's worth of practice, and current non-touch typists remark that it is easier than learning the desktop QWERTY keyboard".