Cache Schemes: Direct-Mapped Cache

RAM Block #   Cache Block # | RAM Block #   Cache Block #
    0 ------------> 0       |     8 ------------> 0
    1 ------------> 1       |     9 ------------> 1
    2 ------------> 2       |    10 ------------> 2
    3 ------------> 3       |    11 ------------> 3
    4 ------------> 0       |    12 ------------> 0
    5 ------------> 1       |    13 ------------> 1
    6 ------------> 2       |    14 ------------> 2
    7 ------------> 3       |    15 ------------> 3

So, to find to which cache block the RAM block $13$ is mapped, for example, we'll divide $13$ by $4$ (the total number of cache blocks,) which is equal to $3$ with a remainder of $1$, so $1$ will be that cache block: $13 = 4\cdot3 + 1$.

As we said before, only one of the RAM blocks that correspond to a cache block will be found in that cache block. For example, only one of the RAM blocks $1, 5, 9, \text{ and } 13$, for instance, RAM block $5$, will be located in cache block number $1$.