In this area, we're looking at the SUBOR hardware and trying to understand how the keyboard works.  To begin with, here are some pictures of the insides.  If you are good with hardware, you can help the effort!

 

Overview

 

 

Cartridge in Slot

 

 

 

SUBOR with the cover off

 

 

Board Interconnect

 

 

 

 

Mainboard Interconnect signals

 

 

 

 

Peripheral Board Interconnect Signals

 

 

 

 

 

 

Mainboard Interconnect Signals

 

 

Mainboard Interconnect Signals

 

 

Peripheral Board Interconnect Signals