Can someone explain this about paging in operating system?

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Frequently, on a 32-bit CPU, each page-table entry is 4 bytes long, but that size can vary as well. A 32-bit entry can point to one of 2^32 physical page frames. If frame size is 4 KB (2^12), then a system with 4-byte entries can address 2^44 bytes (or 16 TB) of physical memory. We should note here that the size of physical memory in a paged memory system is different from the maximum logical size of a process.

How does paging make logical memory space more than physical memory space? Isn't total number of frames in 32-bit CPU equal to 2^(32-12)=2^20 number of frames rather than 2^32 number of frames? If so, isn't a system with 4-byte entry capable of addressing (2^20)*(2^12) bytes of memory?

2 Answers

When we say that a cpu is 32-bit or 64-bit , what it means is that it can point to 2^32 or 2^64 physical page frames respectively. Now if one page frame is of size 4KB (2^12) then the total amount of memory that can be accessed is (2^12)×(2^32)=2^44 bytes or 16TB

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