| 摘要 |
PURPOSE:To convert easily an address in accordance with the specification of a program by providing a titled device with a rewritable table describing the relation between physical and logical addresses and a means for converting both the addresses. CONSTITUTION:When an I/O instruction is started, an I/O processor reads out unit controlling words UCWs. At the reading, a channel address and an I/O device address are set in registers 11, 12 and the leading UCW corresponding to the specified I/O is read out and set in a subchannel memory register SBCR14. The CUW set in the SBCR14 stores the address of a physical I/O device which corresponds to the logical I/O device address. Therefore, the I/O processor can convert the logical I/O device address into the physical I/O device address by starting a channel by the physical I/O device address. Thereafter, the UCWs are accessed by using the logical addresses set in the registers 11, 12. |
