Numerical problem on Access time in Cache memory For a system with two levels of cache, define:


$T_{c_1}$ is the first-level cache access time
$T_{c_2}$  is the second-level cache access time
$T_m$ is the memory access time
$H_1$ is the first-level cache hit ratio
$H_2$ is the combined first/second level cache hit ratio 


Provide an equation for the average access time $T_a$ of a read operation.
Here is the algorithm for a read operation:


Check if the cell is in the first-level cache.
If not, check if it is in the second-level cache.
If not, access it from main memory.


The data you are given allow you to calculate how much time each operation takes, and what is the probability that each of the steps is being taken. Using this, you can calculate the average time of a read operation.