I have since discovered that this info I gave is not correct.
The Homann Designs BoB is an excellent product that complies with the LPT standard. Nothing wrong with that.
However the RetinaEngrave USB controller is NOT LPT compliant. I thought it was. The info on their site suggests that it is.
However the controller uses pin 15 as an output, (PWM laser power control). By the LPT standard as used by Mach3, EMC2, etc. pin 15 is an input.
The BoB that I mentioned above complies with that LPT standard, so that means it will not hook up, pin for pin, with the RetinaEngrave controller.
This can be overcome with a modified connection between the controller and BoB.
Just be aware of that.
Greolt