The process begins:
The Essential controller PCB with AT connector (white case circa 1998-2002??)
Notice there is no memory in the slots labeled U2 and U3 in the upper right corner of the board, the 2 key board halves are unplugged from black connectors labeled J7 (left-you can still see the edge of the PCB an inch away) and J2 (right), the 6 wire power cable is already disconnected from the white vacant plug on the left side. It seems to have a 7 wire capability.
Compared to the Advantage with USB connector (black case circa 2008). Nothing disconnected.
There is one memory chip in the U2 slot.
And the USB board on the bottom of the case (the Essential does not have this)
Essential left side keyboard half. The trackpoint will go in the 4 key intersection (between the 2nd-3rd switches down/1st-2nd switches to the left, from the right side-EXCEPT OPPOSITE on the right keyboard half). Sorry for that, this was the picture that was taken
The space between the switches is 1/4" x 1/4" at the tightest point. I felt better AFTER I wiped the dusty mess with alcohol. Yuk.
The right keyboard half rear view.
The trackpoint will be mounted 2-3 down/1/2 from the right side, pretty much the center of the picture. The PCB "fingers" are not flat, nor on the same plane. I need to make certain there are no traces located on the other (unseen) side or in any possible PCB "layers" in the way of the trackpoint hole that will need to be made. Otherwise..a lot of soldering.
Via mail in a few days, I'm receiving the IBM board with a Trackpoint IV that I will remove to measure and test fit.
Things on my mind:
This needs to work with USB on a Mac. Board is AT, trackpoint will be PS/2. Blue Cube may be partial answer. Will a passive PS/2-USB adapter work for the trackpoint?
I remember reading about Trackpoint drivers for Mac, gotta find that again.
I'll have to cut 1 corner off 4 keys (Y-U-H-J). No coffee that day. Buy smaller chainsaw.
Where to put the 2 or 3 trackpoint mouse buttons. (Under right thumb key cluster?)
Will scrolling work? If not, should a scroll wheel be installed on the left keyboard half?
I'm going to need the parts for adding the F keys row on the top of each of the keyboard halves. I think this part is more art than science. We'll see how many times it takes to get this right. I'm guessing 3.
I'll drag some wires for 3 LEDs from the controller PCB to the right keyboard half, and mount...somewhere.
Wireless would be nice. Reeeeal nice.
Pitch, yaw, roll, height, extension armrest attachment after electronic functionality tests are passing.
Everything should be lime green.
If this goes well at this proof-of-concept stage, I'll do the same thing to my Contoured Advantage and have a few less problems (USB conversions, blah blah).
Lowpoly: Thank you for the TP IV suggestion.
Ricercar: Thank you for the Blue Cube info.