4. Apparatus in accordance with claim 1, further including a plurality of trigraphic keys, and wherein said key responsive means is responsive to the actuation of each said trigraphic key for generating a code signal representative of a sequence of said basic strokes of three.
4. Apparatus in accordance with claim 1, further including a plurality of trigraphic keys, and wherein said key responsive means is responsive to the actuation of each said trigraphic key for generating a code signal representative of a sequence of said basic strokes of three. 8. Apparatus as defined in claim 4, wherein said keys are assigned to positions locating in three horizontal ranks, each rank consisting of about 10 said keys.