Virtual Gate

Question

Consider main memory of size 32GB and blocks of size 32KB. If the propagation delay of comparator is 10T ns (T is the number of tag bits) and the propagation delay of OR gate is 10 ns. What will be the Hit Latency in ns. ?

Comments

Is there nothing about cache size or no. of lines or tags. I think question is not complete.

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Yup...cache size and associativity should be given....

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On these things are given not any extra thing like cache size and associativity

Answer 1

210 ns wat I think will be the answer. The confrigation of this can be assummed like the assosiative cache as no other combinational circuit is given. we will identify the block number and then access the least 15 bit the data. So no of blocks in main memory = 2^20. so 20 bit is the size of TAG, one comparator for each row. and finally an or gate. comparartor will work in parllel. = 20+10 ns = 210ns

Comments

Thanks bro

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we take associative mapping because

in direct map , no. of comparators needed= 1

in associative , no of comparator = no of lines in cache so we need OR gate for ORing of all the comparator

in set associative, no of comaprator = k where k is associativity(no of lines in a set)

nothing is given about associativity so we assume full associative mapping

hence tag bit = 35 - 15 = 20

hit latency = 10 * 20 + 10

                = 210ns

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Thanks