As it turns out, the manual for the HHCH did NOT have the pinout for the specific cable that I have that interfaces to the HHCH. I had to pin it out by hand, as well as my test jig DB25-breadboard cable. The good news is now I can start rebuilding the project from the ground up (I may have ripped all the jumpers off the breadboards last night...). Before I called it a night I was able to get my old test program working with the channel up and down buttons and the serial console. It's not as cool as the LED display, but it's a start.