Thanks to the folks at OSH Park the first production prototype has been assembled. It's quite one thing to cut the board yourself and quite another to have something so very purple and gold...
As usual, click to embiggen.
With all the handshaking issues worked out I now have a very fast and solid transfer protocol, able to load a 40K program in 300 milliseconds.
Work is now ongoing to develop the utility ROM to enable two virtual disk drives 2: and 3:. Basic support is done but I'd love to be able to boot from an SD drive. Achieving this will be a challenge if I'm to retain 100% support for the various DOS versions available for this fine machine.