Data processing apparatus (101 and 102) configured to receive signals from an input sensor (106) arranged to duplicate or replace operations of a keyboard, in which the signals correspond to positions of mechanical interactions with the sensor (106). The apparatus comprises processing means (1202) configured to process data derived from the input sensor including positional data corresponding to the position of a mechanical interaction with said input sensor (106) and a second data type corresponding to the absence of a mechanical interaction with said input sensor. The processing means (1202) is configured to generate data representing a first character in response to processing an item of data of said second type followed by positional data corresponding to a first position, and to generate data representing a different second character in response to processing positional data corresponding to a different second position followed by an item of data of said second type.