A computer system that includes a computer chassis containing an IEEE 1394 bus and peripheral devices. Rather than return an acknowledgement for each received packet, the master returns an acknowledgement only after receipt of a group of packets. The protrusion and the recess are characterized by angled walls oriented at an acute angle with respect to the fastener axis. The processing unit therefore halts communications with the mobile terminals in accordance with the utilization condition and utilization-admission condition. A plurality of outwardly-projecting spacer pins depend from the first major surface of the base, and are adapted for engaging a limited surface area of the face plate.