The XCPU board is the main controller of NEXUS Base Devices and is pri­marily designed for controlling the routing, including redundant lines. It also handles the communication with an external control computer, system management, and controls and monitors all system com­po­nents including power-supply units and backplanes. The external control computer providing the graphical user interface is connected via an RS 232/422 or USB port. The changeover to the USB port occurs automatically. The XCPU 09 now features an Ethernet port simplifying integration into existing computer networks. The USB port can now be used in parallel with the RS 232/422 interface. (The previous XCPU versions only allowed for either the USB or RS 232/422 formats to be used at one time.) A total of three RS 232/422 ports are available: one onboard interface plus two extra ports on the optional XDEM expansion. You select the RS format (RS 232 or RS 422) using a quadruple jumper. The XCPU 09 includes an exceptionally powerful processor providing substantially more power than its predecessors. Therefore, the board can now perform extra tasks which used to be handled by external peripherals. The XCPU 09 implements two critical new functions as optional modules: EBU-R 128 compliant loudness metering and spectrum analysis.