I have a NM-200 with the CD100 control. The loopback DB25 cable on mine is short (1') and connects the BoB to the parallel port. My mill is 10 years old, and I have Novakon do a refurb of the CD100 5 years ago. One thing he did was replace the CNC4PC board with a newer model as the original one was no longer made.

I now run PathPilot on a separate computer that sits atop the CD100. The loopback cable now connects the BoB with the card in the new PC, so the CD100 basically is providing power for the non-computer parts. In theory I could still run Mach3 by reconnecting the loopback cable but haven't had a need to do so. PathPilot is a much better system.

Connections from CD-100 to mill are two cables. One has the 4 axes wires bundled, and the other has the VFD signal.