METHOD AND APPARATUS FOR CONTINUOUSLY UPDATING A DISPLAY OF THE COORDINATES OF A LIGHT PEN

摘要

ABSTRACTA method and apparatus for continuously updating a display of thecoordinates of a light pen as it moves across a display screen involvesexecuting a single iteration of an approximation calculation everyrefresh cycle of the display. The absolute screen coordinates areupdated by the light pen tracking system and converted to applicationparameters written by the host computer into the display buffer workspace. The orthogonal displacements, dx and dy, from a fixed referencepoint are determined. The distance and direction values from thereference point are converted to character form and inserted in thedisplay buffer.