To check if the cache holds the contents of an address, the address is partitioned into three parts.

For example, for a direct mapped cache with 512 sets and a block size of 32 bytes and 32 bit addresses, the cache data capacity is 512 * 1 * 32 = 4096 = 4K bytes and

Parameter	Size	Number of address bits
S	512	9
B	32	5
Tag	-	18

The address is partioned into

Tag	Set	Block Offset
bits 31 - 14	bits 13 - 5	bits 4 - 0