BUS ACCESS ARBITRATION SYSTEM AND METHOD FOR RECOGNITION OF BUS ACCESS

PROBLEM TO BE SOLVED: To provide an arbiter provided with ability to update the priority of respective devices so as to improve the efficiency of a system when the plural devices request access to a data bus. SOLUTION: The arbiter 103 connects the plural devices A-D to a bus 101 and the arbiter 103 decides the priority among the devices based on the relative necessity of the devices A-D. The relative necessity is decided for the respective devices based on the using ratio of buffers 105-109. Gauges 11-115 report the values of the using ratios of the respective buffers 105-109 to the arbiter 103 and the priority is calculated from them. Further, the arbiter 103 considers the speed of the buffer of the respective devices at the time of deciding the priority. In such a manner, the relative priority of the device is dynamically changed when the butter relating to the device reads and writes data through the bus 101.