Analysis of SORD M343SX-III keyboard (part2)

The keyboard board had an MC1489 mounted on it. From this, it was found that it was doing serial communication via RS232C.

The MC1489 works as Quad Line EIA-232D Receivers.

This information was clarified and is shown in the following figure.

Wiring diagram between the keyboard connector and the internal ICs.

I now know the roles of all pins except pin 8 of the keyboard connector.
It is assumed that these signals are eventually connected to the SCI of the HD6303.

The pins of the HD6303's SCI are P23 for RxD and P24 for TxD. If we start from here, the role of the pins in the above diagram will be clarified.

The wiring information from the internal connector to the pins on the keyboard is as follows.

The top view of the DIN8P keyboard connector shows the connector pins as seen from the front. The middle figure is the panel connector, with the connector connections depicted above.

Keyboard panel connector from M68 board.