The first thing to do was take apart a regular keyboard and figure out how it worked.
The little circuit board there has two sets of thirteen terminals. A
keypress is registered when a circuit is completed between one terminal
from the left set and one terminal from the right set. All the rest in
a keyboard is just a matter of getting the circuit to the right place.
So I started out by mapping all the connections from each terminal
to each other terminal. I did this by plugging the circuit board into
my laptop, clipping one end of the aligator clip to a terminal and
touching the other end to every other terminal. Most of the conections
produced nothing at all or perhaps a beep, but sometimes a letter would
pop up and I would record which two terminals were connected. This
allowed me to make a chart
of the entire keyboard for later use.
Next: The basic keys