An access control system for a computing environment in which a number of processing nodes are interconnected to one another via an interconnection system. The purpose of the resistive load is to dissipate excess electrical which may be produced when the inverter acts to slow down the rotating machine, causing the rotating machine to act as a generator. The composition unit 56 carries out composition processing of compositing the image data outputted from the hatching processing unit 55 with the image data outputted from the texture processing unit 54.