A printed circuit keyboard assembly is disclosed comprising a waterproof jacket portion which includes a cover member overlying a sheet of raised key-tip portions, the jacket portion being releasably mounted to a position adjacent the waterproof switch matrix portion. Depression of a key-tip portion will result in the deflection of the switch matrix portion thereby generating binary coded signals representing the key-tip portion depressed. The cover member secured to the jacket portion is constructed to expose a predetermined number of key-tip portions for operation. Means are provided to releasably secure the jacket portion to a position adjacent the matrix portion to allow the interchanging of jacket portions each having different numbers of key-tip portions available for depression to meet changing business conditions.
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