Apparatus for collecting encoded data for supply to computers; Apparatus for computer aided design; Apparatus for computer aided manufacture; Apparatus for computer numerical control of machines; Apparatus for controlling computer programmes; Apparatus for controlling the operation of machines (computer); Apparatus for data communications between computers; Apparatus for inputting information into a computer; Apparatus for linking computers; Apparatus for linking computers into networks; Apparatus for protecting computers from electrical power supply faults; Apparatus for receiving information from a computer; Apparatus for use in communications between computers; Computer apparatus for transmitting data