| 摘要 |
PURPOSE:To detect memory mapped I/O in a central processing unit by giving memory mapped I/O information to a page descriptor and storing it in a TLB. CONSTITUTION:MPIO information 323 is given to a page descriptor 32, and a page indicated by the page descriptor is mapped in an I/O space if this IO information is '1', and the page indicated by the page descriptor is in a memory space if IO information is '0'. This MPIO information is recorded in the TLB. A part except an intra-page offset of a VAR 11 of the effective address sent from an effective address calculating part is compared with virtual pages stored in a virtual address part of the TLB; and if a coincident virtual page number is found, the entry in a data memory part of the TLB corresponding to the virtual page number is read out to an RAR 15. The read actual page number in the RAR 15 is combined with the intra-page offset of the virtual address of the VAR 11 to generate an actual address, and this address is outputted to an address bus 110.
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