A data transfer flow control system for a packet ATM communications system includes a plurality of nodes interconnected by transmission links. In some embodiments, a method of forming the recessed access device includes forming a device recess in a substrate material that extends to a first depth in the substrate that includes a gate oxide layer in the recess. If necessary, the work notification supplies the prescribed service level for the host channel adapter. The invention further provides a method of polishing a substrate comprising the use of the polishing pad.