I would like to say there is progress, as I am steadily working on it, but progress is still slow. I did learn that the board has two processors on it, an 80c196 and an 8088-2 (that part isnt terribly hard to figure out). What is new though, is that it appears to use the 80c196 for communication ( the ISA card, Axis controller and optional external keyboard all have one). The 8088-2 runs the actual axis positioning, and the 80c196 drip feeds it commands. The volume of comm traffic on the RS-485 link between the PC and Axis controller (AC) is downright bewildering- the below program:
M06 T02 G43 H02
Yields approximately 500 lines of communication on the PC<-->AC RS485 link . There is also a data link between the 80C196 and 8088, and that yields a much more logical 100ish lines. I have been trying to decode this traffic, and have had some success -I believe I have identified the startup sequence the control sends to the machine when WinNC first starts for example. What I dont know yet (but want to) is how that sequence is shaped by the MSD file and others.
Additionally, I realized the machine uses a heartbeat signal ( a pattern of 00's) every 58-59 seconds when idle. This is not logged with the debug options in WinConfig. I found this using a cheap Ebay ($8) USB to RS485 converter-hooked up in parallel to the pins on the comm cable between PC and AC, it has no trouble logging traffic on the RS485 line.
Happy to share files if there is interest.