I have an old keyboard made by Wyse for their line of 286 based computers back in the 80's. It connects directly to the processor card via a 4-wire cable with connectors on it that are the same as you find on the handset of a telephone; like RJ-11, but narrower. They provided an adapter that allows a keyboard with a DIN connector to connect to the computer, but not one that allows their keyboard to connect to another computer. I'm trying to make a cable that will serve that purpose, and at the same time convert from the AT style DIN to PS/2 Mini-DIN. Even though all these cables have different numbers of pins, they all have the same number of signals, data, +5 volts, clock, and ground.
I've tried connecting the signal lines to where they should be as follows:
Wyse Adapter Signal Standard Keyboard Pinout on Mini-DIN Yellow Data 1 Green +5v 4 Red Clock 5 Black Ground 3
No go. I also tried swapping a couple of things based on some notes from a Wyse web page about another of their keyboards. Didn't help.
The next thought I have is the brute force method of trying each signal/pin combination. That's where the math question comes in. I think that's 24 unique combinations, but it's been too long since I've had to use that knowledge for me to be sure. Does anyone know a way to generate all unique combinations of 4 things? I'm starting with the brute force method to generate that list, too, but it would be nice to verify my thinking, and to make sure that I'm not off by some order of magnitude, or something.
Here's how I arrived at 24:
Data Ground +5v Clock Yellow Black Green Red 1 3 4 5 1 3 5 4 1 4 3 5 1 4 5 3 1 5 3 4 1 5 4 3
Since there are four numbers, and when you pick one of them as a constant, there are six combinations of the other 3, then there should be 6 * 4, or 24 combinations, total.
At least, that's what my rusty math tells me. Am I on the right track, or do I need some mental WD-40? This vaguely reminds me of factorials for some reason. 4! is 4 * 3 * 2 * 1 = 24.
As far as some other reason the keyboard won't work, I wonder if there might be some difference in clock speed that could be a problem. That's just a wild guess; I really don't know much about this sort of hardware design.
-- Regards,
Dick Steffens http://home.comcast.net/~rsteff/
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