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what is the physical memory size when each page table entry also contains 3 bits for book keeping?

consider a logical address space of 2^30 bytes and Ps=1kB,if the total size of memory requires for storing the page table is 2 MB,what is the physical memory size when each page table entry also contains 3 bits for book keeping??

A=4MB

B=8MB

C=3MB

D=1024KB

1Comment
Parimal Andhalkar @parimal_andhalkar
15 Jan 2016 10:59 pm

ans B

no. pages = 2^30 / 2^10  = 2^20

Page table size = No. of entries * size of entry 

2 * 2 ^20 = 2^20 * entry size

Page table entry size = 2B = 16 bit

3 bit used for book keeping

frame number bits = 13 

Physical address bits = 13 + 10 = 23 bits

Physical address space = 2^23 = 8 MB