An application specific integrated circuit uses a dedicated interface between core logic and an independent SerializerDe-serializer bus to provide SBus capabilities to the core logic. The sensor unit measures the moving state of the sheet when the sheet is located at the measurement position, and measures a moving state of a surface of the rotary member when the sheet is not located at the measurement position. A service provider layer is adapted to relay transaction requests passed from the transaction manager to associated hardware for execution. Furthermore, the directory group may employ a plurality of locks to control access to objects in each directory.