US. Patent Mar. 23, 1989 Sheet 1 0f 10 4,817,034 46 I0 VIDEO @ J 50 PAPER FEEDER / ‘2 <——l_) f MICRQ- /48 COMPUTER PLOTTER , 502 lE’MROGFZAM /I6 mSK MEMORY / '8 EMORY 2 O DIGITIZER PAD / l4 RAM BUFFER —A 22 504