Test by Bikram | Computer Organization and Architecture | Test 2 | Question: 12

Question

A $4$ way set associative cache with a size of $32$ KB has line size $16$ Bytes. There is a Byte addressable main memory with a size of $256$ MB, then which of the following Main Memory block is mapped on to the set $'0'$ of Cache Memory?

• A. $(FCEE90B)16$
• B. $(FECF10C)16$
• C. $(CFEE09B)16$
• D. $(CDDE00B)16$

Comments

?wht

Answer 1

Total cache size is 32 KB = 2⁵ * 2¹⁰ Bytes .

Total number of sets = (2⁵ * 2¹⁰  / 2⁴ * 2² ) =  2⁹

9 bits used for set .

15 bits for tag and 4 bits for word .  

 Tag | Set | Word

    15 | 9 |  4

CDD  111 0 0000 0000  B  hence answer is option D .

Comments

@bikram sir

CDD  111 0 0000 0000  B  hence answer is option D .  ?how?(above this line i got all things)

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@hem chandra joshi  

See ,we have to go with each options here. 

for option D , which is in hexadecimal .

 CDDE00B  we can write as 

CDD E 0 0 B

= CDD 1110 0000 0000 B

we can write this way and this memory block mapped to set '0' 

here  0 0000 0000 is representing set '0' of cache memory , in CDD  111 0 0000 0000  B we  took lower 9 bits for set.

E = 1110

as question asked " which of the following Main Memory block is mapped on to the set '0' of Cache Memory" .

 here we have to go with each option. only this option have set '0' of cache memory.