Data general protocol

Hi gang, does anyone know of or have any kind of protocol data for Data General keyboard<-->terminal connection? I've got a leaf spring 3rd gen board with a db-9 connector and it's using 6 lines -- 2 serial in/out pins, and 4 others called KBIRQ, KBC RESET, CLK COM and SCLK.

I'm going by some info in this patent: -- and I found a pinout of the connector but have very little info on the wire protocol. It seems to want 2 pulses of KBC RESET to start.
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Unread post15 Sep 2018, 02:31

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patent says KBIRQ is generated by keyboard when it has something to say (also periodically, every 8 keyboard scans), along with the CLK.
So after reset pulse you should see periodic KBIRQ pulses and clock.

Connect scope to serial in, press keys, see what's there.

It seems from description that terminal sends LED and bell status to keyboard. Using format gleaned from ^^, try to send 1,2,4,8.. to the keyboard, see what happens.

Without the scope it's nigh impossible to figure out.

Unread post16 Sep 2018, 22:59

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