COMPUTER PROGRAMS RECORDED ON MAGNETIC MEDIA; BATTERIES; INTERCONNECT CABLES; SIGNAL INTERFACE MODULES AND UNITS; BATTERY CHARGERS AND DISCHARGERS; POWER SUPPLIES; LASER SCANNERS; CONTACT SCANNERS; NON-CONTACT SCANNERS; AND, CONCENTRATORS AND PROTOCOL CONVERTERS FOR PROVIDING BIDIRECTIONAL DATA COMMUNICATIONS BETWEEN A PLURALITY OF BAR CODE READERS AND PRINTERS AND A HOST COMPUTER PAPER KEYBOARDS AND PRINTED BOOKLETS DEALING WITH COMPUTER PROGRAMS