Abstract: The specification discloses a method and apparatus for setting and varying margins, line spacing and printing direction of a data printing machine by a machine user before and during printing by use of a keyboard with push-button control which is coupled to a digital controller to input information about the actual and the desired location of a print head relative to a printing surface, in response to which the controller outputs signals which control relative motion of the print head and indexes its relative position, from the actual to the desired direction and location.