Patent ID: 7830902

Claim:
An arbiter mounted on a crossbar in which a plurality of units capable of issuing a request are connected, for selecting a request among requests issued by the units each of which belongs to one of a plurality of groups of units, the arbiter comprising: a plurality of first request selection parts, each of the first request selection parts corresponds to one of a different groups of units, and that selects a request among requests issued by the units belong to the same group of units corresponds to the first request selection part, respectively; second request selection part for selecting a request among the requests selected for each of the groups of units by the first request selection parts; and selection control part for enabling the second request selection part to select a request among requests issued from the groups of units according to a predetermined priority of each group of units among the plurality of groups; wherein the priority of each group of units among the groups is changed at prescribed time intervals.