ASSOCIATIVE MEMORY o Associative memory-parallel search Page Frame Address translation (p,d) If p is in associative register,get frame out Otherwise get frame from page table in memory
ASSOCIATIVE MEMORY Associative memory – parallel search Address translation (p, d) If p is in associative register, get frame # out Otherwise get frame # from page table in memory Page # Frame #
PAGING HARDWARE WITH TLB logical address CPU p d page frame number number TLB hit physical address d TLB p TLB miss physical memory page table
PAGING HARDWARE WITH TLB
MEMORY PROTECTION o Memory protection implemented by associating protection bit with each frame o Valid-invalid bit attached to each entry in the page table: 。“valid”indicates that the associated page is in the process'logical address space,and is thus a legal page 。“invalid”indicates that the page is not in the process' logical address space
MEMORY PROTECTION Memory protection implemented by associating protection bit with each frame Valid-invalid bit attached to each entry in the page table: “valid” indicates that the associated page is in the process’ logical address space, and is thus a legal page “invalid” indicates that the page is not in the process’ logical address space
VALID (V)OR INVALID (I)BIT IN A PAGE TABLE 0 1 2 page 0 00000 frame number valid-invalid bit page o 3 page 1 0 2 page 1 1 3 4 page 2 4 page 2 23 5 7 page 3 8 6 5 9 page 4 7 page 3 10,468 0 page 5 8 page 4 12,287 page table 9 page 5 page n
VALID (V) OR INVALID (I) BIT IN A PAGE TABLE