| 摘要 |
PURPOSE:To shorten the queuing time due to access competition by executing the access competition with respect to a shared memory from plural controllers at every address corresponding to an I/O device. CONSTITUTION:While the controller DKC 1 executes the access lock of a disk device DKU 1, an activation for accessing the DKU 2 from the DKC 2 is outputted through an access signal line 6. Then, referring to an access lock circuit 6, a competition solving control circuit 10 recognizes the presence or absence of the access lock. An I/O address corresponding to the DKU 2 accessed by the DKC 2 from an address output part 9 and an I/O address in the middle of the access lock from an I/O address register 11 are outputted to a comparator circuit 13. If both addresses are different, the results are transmitted to the competition solving control circuit 10. If the compared results are not equal in the comparator circuit 13, said circuit 10 permits the access even if the DKU is access-locked. |
