What they said!! I was reluctant to move from Mach3 to Mach4 and when stuff didn't work like I expected I thought it was screwed up, but I finally just made the switch and am very happy I did. It runs the machine WAY better, hit Feed Hold and it stops right now, for example, and it's very customizable but you have to figure out how because it ain't Mach3!! If you come from Mach3, that's the biggest hurdle, Mach4 isn't Mach3.