Abstract: A processing unit connectable to a data communications network has a data carrier reader operable to read a network address from a hand insertable data carrier, wherein the processing unit is operable to use the network address from the data carrier for communicating via the data communications network. A processing unit forming part of a computer system may be readily replaced by a replacement processing unit, and arranged to continue communicating via the communications network, by using the same network address as the original processing unit read from the data carrier. The data carrier may be a Smart card or the like. A method of operating a computer system may therefore comprise connecting the processing unit to a communications network, loading a data carrier into the data carrier reader, arranging for the network address to be read from the data carrier, and arranging for the processing unit to use the network address read from the data carrier to communicate via the network.

Abstract: A system (e.g., a power supply) is presented which allows a user to electrically couple a common ground electrical potential of a circuit (e.g., a power supply circuit return) to, or electrically isolate the common ground electrical potential from, an earth grounded chassis, without having to open the chassis. The system may include a metal bolt and nut, wherein the nut is coupled to an electrically conductive bracket. The bracket is mounted upon a printed circuit board and electrically coupled to the common ground electrical potential. When an insulating bushing is installed in a hole in the chassis adjacent to the bracket, and a threaded shaft of the bolt extends through aligned holes in the insulating bushing, an insulating member positioned between the bracket and the chassis, and the bracket, and the threaded shaft engages the nut, the bolt holds the insulating bushing in place, and the bracket is electrically isolated from the chassis.