Abstract: A miniaturized single-hand keyboard for computers, PDAs, cellular phones and other portable electronic devices. The keyboard has only four keys, each operated by one finger. Characters are generated by depressing a single key or a combination of two keys in a ‘composite keystroke’. A composite keystroke is performed by depressing a combination of two keys in a predefined order and then releasing them in a predefined order. In the normal mode, three simple keystrokes and 24 possible composite keystrokes are used to generate each of the 26 alphabetic characters and a space. One of the four simple keystrokes (optionally followed by another simple keystroke) is used to enter one of five other modes (Shift, Numeric, Language, Alternate and Control), which support generating uppercase, numeric, language specific and special characters and cursor control and editing control codes.