I have transcribed the wiring diagram of the SORD M68 keyboard into a more abstract circuit diagram.
74166 sends the keyboard press information as a serial 8-bit data. Assuming it sends the same data as the SORD M23, I believe it would be either 04h (0000 0100), 08h (0000 1000), 10h (0001 0000), 20h (0010 0000), or 40h (0100 0000). In any case, an 8-bit sequence with one bit set should be transmitted.
