The issuance timing of commands received from and transmitted to among a plurality of processing units is controlled efficiently. An execution command storage unit 222 stores execution commands, received from an external command transmitting entity, where a predetermined upper-limit number of execution commands to be stored is set. An execution command issuing unit 230 retrieves the execution commands stored and issues them to a command execution entity. An adjustment command storage unit 224 stores the adjustment command, transmitted from the command transmitting entity, to adjust the issuance order of the execution commands. A storage area for storing the execution commands to be stored in the execution command storage unit 222 and a storage area for storing the adjustment command to be stored in the adjustment command storage unit 224 are separately provided. When the adjustment command is stored, the execution command issuing unit 230 issues an execution command received after the reception of the adjustment command, on the condition that the issuance of execution commands received prior to the reception of the adjustment command has been completed.
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