A system for performing computer-based operations is disclosed. The system includes a printer for printing visible information and coded data tags on a surface substantially simultaneously. Each coded data tag encodes a region identifier for uniquely identifying a description of a region on the surface, and a position in the region. The description associates at least one instruction with one or more positions in the region. The system further includes a sensor for sensing at least one coded data tag and for generating a signal indicative of the sensed coded data tag. A computer system receives the signal, determines the region identifier and the position, relates the position to the at least one instruction using the description, and executes the at least one instruction.