Acoustic couplers; couplers for data processing; interfaces for computers; magnetic data media, optical data media, optical compact discs; microprocessors; modems; monitors (computer hardware and computer programs), computer peripheral devices; optical character readers for computers; scanners (data processing equipment); facsimile machines; electronic pens; audiovisual teaching apparatus; computers; calculating machines; computer memories; recorded computer operating programs; comparators; apparatus for recording, transmission or reproduction of sound or images; integrated circuits; mathematical instruments; data processing equipment; optical apparatus and instruments; transistors; projection screens and devices; radiological apparatus