Question

In a paged memory, the page hit ratio is 0.35. The required to access a page in secondary memory is equal to 100 ns. The time required to access a page in primary memory is 10 ns. The average time required to access a page is :

a) 3.0 ns
b) 68.0 ns
c) 68.5 ns
d) 78.5 ns

Answer 1

To calculate the average access time for a page in paged memory, use the provided page hit ratio (0.35) and the access times for primary (10 ns) and secondary (100 ns) memory. After calculations, the average access time comes out to be 68.5 ns.

Step-by-step explanation:

The question pertains to calculating the average access time for a page in paged memory, given a certain page hit ratio and access times for primary and secondary memory. The page hit ratio is the probability that the page we want is already in primary memory, which in this case is 0.35 or 35%. The remaining 65% (1 - 0.35) of the time, a page fault occurs, and we have to access secondary memory.

The calculation for the average access time (AAT) is as follows:

• AAT = (Hit ratio × Time to access primary memory) + (Miss ratio × Time to access secondary memory)

Plugging in the provided values:

• AAT = (0.35 × 10 ns) + (0.65 × 100 ns)

This gives us:

• AAT = (3.5 ns) + (65 ns)

Adding these together, the average access time is:

• AAT = 68.5 ns

Therefore, the correct answer is c) 68.5 ns.