Key input means providing common key identifying and display driving

Abstract

A keying input apparatus is provided which includes; a bit pattern generator responsive to a clock signal for generating different bit patterns of four bits, in a bit sequence and a decoding matrix for converting the different bit patterns at every fourth bit, into individual digit timing signals. A plurality of key switches are connected at one end thereof with corresponding ones of the digit timing signals and connected to a common terminal at the other ends thereof, to drive a gate responsive to the common connected output of said key switches for allowing a coded signal representative of a particular depressed key to be withdrawn from the bit pattern generator and transfer it to a circulation register for storing the coded signal. Depression of a given key thus enables the gate at a corresponding digit timing to load a coded signal corresponding to that digit timing in the register, so that the coded signal as stored in the register uniquely identifies the depressed key.