Abstract: A digital switch for selectively interconnecting a plurality of devices, including microcomputers, in a network comprises a plurality of inputs, a plurality of outputs and selectively operable interconnections which include decoding means for decoding data and acknowledgement bit packets, clock means, and means for generating under control of clock signals output bit packets having bit signals corresponding to bits of input bit packets.

Abstract: In a reading machine in which a record such as a film record is read by scanning with a monitoring beam which is then detected by a photo-sensor, a sheet of photo-sensitive material is placed against the record and after each part of the record has been read it is traced with an activating beam which activates the photo-sensitive material and thus changes the color or density of the line as seen when the combination of the record and the photo-sensitive film is observed. The part of the record which has been read can thereby be distinguished easily from that which is still to be read, eliminating risk of re-reading.