New CNC Mill

I just acquired my son's Industrial Hobbies vintage 2006 CNC mill. It has 81V motors and Rutex 2020-0506 drivers. The computer no longer exists, but it was successfully working on Mach 3 at one time.
I can't identify the controller board. I would like to get this thing up and running again.

Questions...

- Is there a USB controller board that is compatible with Mach 3 and the Rutex 2020 boards?
- Do USB controller boards (if they exist) require use of USB driver boards (if they exist)?
- How do I identify the controller board I have? It's a parallel interface board with no markings.

thanks, rex