Electronic apparatus push button keyboard assembly

Claim 1

A keyboard input assembly comprising a plurality of manually operated push button switches divided into first and second groups, each of said switches having a first and second fixed contact and a movable member for contacting both said first and second contacts when said button switch is operated and for remaining out of contact with said first and second contacts when said switch is not operated, a plurality of logic means, each said logic means corresponding to one of said manually operated switches, and each said logic means having at least a first input means and a second input means and each said logic means being adapted to produce a predetermined signal in response to said first and second inputs of said logic means being coincidentally energized, said logic means being divided into first and second groups, a first input of each of said logic means in said first group being coupled to all of said plurality of said first fixed contacts in said first group of manually operated switches, each said first input of said logic means in said second group being coupled to all of said first fixed contacts in said second group of manually operated push button switches, a second input of each logic means in said first group of logic means being coupled to the second input of an individual logic means in said second group of logic means, and being further coupled to the second fixed contact of one manually operated push button switch in said first group and one manually operated push button switch in said second group of manually operated push button switches, so that each of said first and second inputs of said logic means are coincidentally energized by a fixed power supply in response to said manually operated push button switch corresponding thereto being actuated, the movable member of each of said push button switches being continuously coupled to said power supply.