Here's my setup: Reprap Prusa, RAMPS 1.4, Arduino Mega 1280, Makergear Hot End, OSX host (Lion) The only firmware and software combo I've got somewhat working is Sprinter + ReplicatorG. I can jog X and Y and E in both directions and it does read the temp correctly, but it only lets me jog Z in one direction and the extruder heater won't come on. The Z motors are wired correctly, they work corrby pgnat - RAMPS Electronics