Electrical and electronic apparatus, instruments and devices, comprising-- amplifiers, distributors for electrical signals comprising video, audio, data, test, control, television and telephony signals, distribution amplifiers, baluns, cable connectors, circuit boards, re-clockers, automatic gain control devices, equalizers, filters, hum buckers, hum cancellation devices, [ computer programs for television and/or video production and editing, ] computer programs for performing electronic system diagnostics, network management software for controlling the distribution of electrical signals comprising video, audio, data, test, control, television and/or telephony signals, [ data storage devices comprising optical disks, magnetic disks, read-only memory and random access memory having stored thereon computer programs for television and/or video production and editing, for performing electronic system diagnostics and/or for controlling the distribution of electrical signals comprising video, audio, data, test, control, television and/or telephony signals, ] electrical cables, electrical controls and control panels, interface panels, electrical signal converters and translators, analog to digital converters, digital to analog converters, electrical signal delay modules, electrical signal encoders and decoders, electrical signal generators, electrical signal interface units, electrical signal mixers, electrical signal modulators and demodulators, electrical signal routers, electrical signal switchers and switching matrices, fiber optic cables and cable connectors, fiber optic transport systems comprising optical transmitters and optical receivers, fiber optic modems, fiber optic transmitters, fiber optic receivers, fiber optic switches, fiber optic routers, machine controllers, optical signal multiplexers, optical signal receivers, optical signal repeaters, optical signal transmitters, media converters, ethernet fiber optic media converters, RGB and VGA media converters, computer networking hardware, video networking devices, namely, hubs, switches and routers, optical networking devices, namely, hubs, switches and routers, oscillators, power supplies, video signal keyers, loss detectors, level meters, signal clampers, and video signal processors and parts therefor sold as a unit