good question shows my lack of electronics knowledge, 4 brush dc motor, approx. 4" dia x 12" long, 250 ct encoder on end of ea, belt driven ball screws ?x reduction (count in pc based control built by CNC Automation of Amherst NH is 12000/inch) driven by westamp A711X series servo drives. motion board is obsolete one from mid 90s by Mechtronix. want all old stuff gone, new either Mach4 or UCCNC. if I go with Mach4, most likely PMDX, but still thinking using likely UCCNC's biggest amps. does that help? leaning PDMX because of what I read here of Mr Stallings posts, and a telcom with them, seem willing to help with my questions. does that help? have pics.