The size of the cache tag directory is (A) 160 Kbits (B) 136 Kbits (C) 40 Kbits (D) 32 Kbits

Question

A computer has a 256 KByte, 4-way set associative, write back data cache with block size of 32 Bytes. The processor sends 32 bit addresses to the cache controller. Each cache tag directory entry contains, in addition to address tag, 2 valid bits, 1 modified bit and 1 replacement bit.

The size of the cache tag directory is 

(A) 160 Kbits 

(B) 136 Kbits 

(C) 40 Kbits

(D) 32 Kbits

Answer 1

(A) 160 Kbits

TAG control ler maintains 16 + 4 = 20 bits for every block 

Hence, size of cache tag directory = 20 x 213 bits = 160 Kbits