CODEWITHSUNDEEP
memory-managementoperating-systempaginationvirtual-memory
devoured elysium
devoured elysium

Reputation: 105037

Determining the physical address from a virtual memory's page table

Assuming a virtual memory paging system with pages 4k long, I was given the following table

      P A M
0x003 1 1 0
0x04A 0 0 0
0xA78 1 1 1
0x0A1 1 0 0
0x000 1 0 0

*(P = presence digit, A = access digit, ; M = modified digit)*

and asked what is the real address of 0x003A78.

I am a bit lost here, I guess the idea is to decompose 0x003A78 in 2? That'd be 0x003 A78, so it'd be (2 * 4k) + 0x078 ?

Is this it or am I completing off on this?

Upvotes: 1

Views: 824

Answers (1)

ruslik
ruslik

Reputation: 14870

The first colomn would be "number of physical page". You just have to use the number of virtual page (0x3A78 / 0x1000, that is 3) as index to that table.

The page is present, so the physical page number is correct, that means that the physical address would be 0xA1 * 0x1000 + 0xA78, or 0x0A1A78.

Upvotes: 2

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