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Im studying for OS-finals and I cant figure out the difference.

A page is a chunk of addresses e.g 0-4095. This maps to 4kB of memory. This page is 4kB big. But according to the litterature the Page table entry is around 4 Bytes big. I thought Page Table Entry are the same as a page.

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AFAIK, the page table entry doesn't contain the page itself. Rather, it contains the address of the physical memory chunk that the particular page in the table is mapped to. This address will be 32-bits (4 bytes).

Page table mechanism

In this example, the page table entry contains the address of the physical memory chunk (frame). Knowing the offset, we can find the actual address in the physical memory.

Hope it helps.

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  • $\begingroup$ The page table entry is the field marked "f" in the page table array here above. It is 32 bits wide on many ISA (x86, ARM, SPARC...).Usually the tables have several layers, with both PTE : Entries and PTD : Descriptors, which contains pointers to next level tables. $\endgroup$ – TEMLIB Apr 21 '16 at 22:51

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