In a paging system, it takes 30 ns to search translation Look-a-side Buffer (TLB) and 90 ns to access the main memory. If the TLB hit ratio is 70%, the effective memory access time is :
(A) 48ns
(B) 147ns
(C) 120ns
(D) 84ns


Answer: (B)

Explanation:

Effective access time = Hit ratio*Time during hit + Miss Ratio * Time During Miss
=0.7*(30+90) + 0.3 (30+90+90) 
=84 + 63
=147 ns

So, option (B) is correct.

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