Abstract: Alphanumeric keyboards are described for use with one hand to enter data. Each keyboard includes a plurality of individually movable alphanumeric keys that are each assigned a different letter of the alphabet. The keys are positioned side-by-side in multiple rows such that when four fingers of one hand are positioned over a home position, these fingers can depress all the letters by moving less than three key positions from the home position. Specialized key features are provided on the keyboard to facilitate the execution of multi-key combinations.A right-hand keyboard and a left-hand keyboard are disclosed as interchangeable with a conventional keyboard in a supporting shell. Alternatively, both the right-hand and left-hand keyboards are supported on opposite sides of a common rotatable member pivotably mounted in the supporting shell.