A substrate processing apparatus including a frame, a SCARA arm mounted to the frame at a shoulder joint having two links with at least one end effector dependent therefrom, the links defining an upper arm and a forearm, each end effector pivotally joined to the forearm at a wrist to rotate about a wrist axis, and a drive section with at least one degree of freedom operably coupled to the arm to rotate the arm about a shoulder axis articulating extension and retraction, wherein the end effector is coupled to a wrist joint pulley so that extension and retraction effects rotation of the pulley and end effector as a unit about the wrist axis, and wherein a height of the end effector is within a stack height profile of the wrist joint so that a total stack height is sized to conform with and pass through a pass-through of a slot valve.