I'm able to get it to do one notable thing and it only works with a single key (backslash).
If I put pull up resistors on all of the lines we've talked about (kbd strobe, o, p, 1-7), I observe the following things:
- kbd strobe goes up and down, but does it in pulses
- kbd o and kbd p stay high
- kbd 1, kbd 2, and kbd 4 go up and down (no pulses)
- kbd 3, kbd 5, kbd 6, and kbd 7 stay high
If I start hitting the backslash key, the following things happen:
- kbd 1, kbd 2, and kbd 4 go low and stay low as long as I press the key
- kbd strobe also seems to get interrupted, but keeps doing its pulses
Here's a video of me hitting backslash 8 times:
And the accompanying screenshot:
It's a shame that I haven't been able to find much documentation about this keyboard. IBM seems to have very extensive documentation, and I've found good information about much more obscure keyboards in the past, but maybe this one was so integrated into the computer that it was an afterthought. Either that or it's just really hard to find good google results because of all the other links pertaining to the machine in general.
So here I am again, excited by this tiny clue but still lost as to where to go from here.