Need help reversing a matrix

[002]

Hi guys,

I need some help reversing the matrix of the keyboard in the IBM PC Convertible.
I think I've figured out the rows but I'm not sure how I'm supposed to figure out the columns.

For example I know that for Q,W,E,R,T,Y,U,I,O,P the pin is the same on the controller at the top.
What do I need to do from here?

[002]

Example:

[sixty]

Did you read this guide?

Basically next you would have to just use the other pin of the switch and check it against all the controller pins again. If you can't get the circuit to close because of the diodes, you might have to use a different multimeter mode. Alternatively you can trace them visually, but it's gonna take a much longer time.

[002]

I did read it - it's what inspired me to start this in the first place; but the second pin of the switch doesn't give me a result when I slide the tester along the controller pins.

[sixty]

Probably because of the diodes then. I had the same problem on one of the keyboards I tested and had to end up tracing it visually.

[002]

I think I've done it right.
Doesn't seem like a very imaginative matrix?