Hitachi, Ltd.

Takuya Iizuka

Satoru Watanabe

Toshimitsu Ando

In a system in which data transfer interfaces respectively of apparatuses are connected via a bidirectional bus to each other, the availability ratio of the bus is improved. An apparatus to issue read and write requests includes a write buffer to store write data and a bus changeover unit to monitor an operation status of the bus for a read data transfer. The apparatus immediately sends a read request via the bus to a communication partner and then receives read data via the bus from the partner. A write request and associated write data are once stored in the write buffer. When a predetermined number of write data is accumulated, a data transfer direction of the bus is changed if the bus is not being used by a read data transfer to successively transmit the write requests and write data thereof to the partner.

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Hadano, Japan

Takuya Iizuka