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In a computer system, memory mapped access takes 100 nanoseconds when a page is found in TLB. In case the page is not TLB, it takes 400 nanoseconds to access. Assuming a hit ratio of 80%, the effective access time is:

In a computer system, memory mapped access takes 100 nanoseconds when a page is found in TLB. In case the page is not TLB, it takes 400 nanoseconds to access. Assuming a hit ratio of 80%, the effective access time is: Correct Answer 160ns

Data:

Hit ratio = H = 80 % = 0.8

Miss ratio = (1 – H) = 20 % = 0.2

TLB access time = T

Main Memory access time = M

Page is found = (T + M) = 100 ns

Page is not found = (T + 2 × M) = 400 ns

Formula:

Effective memory access time = H × (T + M)+ (1 – H )(T + 2 × M)

Calculation:

Effective memory access time = 0.80 × (100) + 0.20 × (400)

= 80 + 80

= 160

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