9 ELECTRONIC COMPUTERS AND ELECTRICAL DATA INPUT AND OUTPUT APPARATUS FOR USE THEREWITH, ELECTRONIC VISUAL DISPLAY UNITS; KEYBOARDS AND KEYPADS, ELECTRONIC TABLETS AND STYLI FOR USE THEREWITH ALL BEING DATA INPUT APPARATUS FOR USE WITH COMPUTERS; ELECTRONIC DIGITISERS, PLOTTERS AND PRINTERS, ELECTRONIC DRIVES FOR DISCS, PAPER TAPES AND MAGNETIC TAPES; PHOTOELECTRIC LIGHT PENS, ELECTRONIC APPARATUS FOR TRANSFERRING PLANS OR DRAWINGS TO COMPUTER MEMORIES; PARTS THEREOF FOR ALL THE AFORESAID GOODS; COMPUTER PROGRAMS; COMPUTER-AIDED DESIGN UNITS FEATURING COMBINATIONS OF THE ABOVE-DESCRIBED ITEMS