Chapter 5 - Text Entry Using a Small Number of Buttons

Abstract

This chapter discusses text entry using a small number of buttons, focusing on systems in which the user enters text by pressing keys or buttons and in which more than one character or letter is assigned to each button. Such keyboards are ambiguous because there is an uncertainty as to the intended symbol when a key is pressed. There is a recent worldwide interest in such ambiguous keyboards because of mobile computing, for which space is limited. Different keyboards can be designed for different tasks. Even though commercial de facto standard keyboards have predominated in the past, keyboard efficiency has become more important with the widespread adoption of ambiguous keyboards. The chapter presents ways to measure entry efficiency and expect the application of these techniques to lead to a better keyboard design. Even though ambiguous keyboards have a reduced complement of keys, users still require access to a large set of characters, including the alphabet, numbers, symbols, and editing keys.