I finally got my own build of the UD-80 working. I had a little trouble initially since the first 6803 I tried seem to be either bad or fake, but after popping it out and replacing it with another things started working correctly. I still need to make the cable for connecting it to my PX-8, but I was able to use a standard 9 pin serial cable to get my laptop to download the the drivers via filink. I also put together an updated BOM list with digikey/mouser part numbers I used for ordering if anyone else is interested. Thanks a lot to @fjkraan for his work on reverse engineering this piece of hardware.
