A data processor for speedier processing of input data includes a data processing system for executing a text editing process and a text printing process by the time slice method and a preference control unit for selecting between the above processes. When data is entered into the processor, the entering process or text editing process is generally preferred to the text printing process. Therefore, no delay occurs in inputting data through a keyboard from data entry to its display. If desired, it is possible to prefer the text printing process to the text editing process.