1. A data device, comprising: a housing; display means included on said housing for displaying a plurality of display screens to a user of said data device; input means included on said housing for inputting at least one of user response data and user commands to said data device; a processor contained within said housing which is adapted to control the operation of said data device; and memory means coupled to said processor for storing operating software for operating said data device and for storing an input program defining a user interface for said data device, whereby said data device can be easily programmed and re-programmed to be used for a plurality of different applications.