PROSOFT MVI56-LTQ The actual data obtained from the main memory

The data block (cache row) contains the actual data fetched from the main storage. This label contains (part of) the address of the actual data retrieved from main storage. Flag bits are discussed below.

The “size” of a cache is the amount of main memory data it can hold. This size can be calculated by multiplying the number of bytes stored in each data block by the number of blocks stored in the cache. (Tag, flag, and error correction code bits are not included in the size, [17] although they do affect the physical area of the cache.)

The effective storage address accompanying the cache row (block) is split (most significant bit to least significant bit) into labels, indexes, and block offsets. [18] [19]

The index describes which cache set the data is placed in. The index length is bits for s cache sets.

Block offset specifies the required data within a block of stored data within a cache row. Typically, effective addresses are in bytes, so the block offset length is bits, where b is the number of bytes per data block. This tag contains the most significant bits of the address, which are checked against all rows in the current collection, which has been retrieved by the index, to see if the collection contains the requested address. If so, a cache hit occurs. The length of a label in bits is as follows:

Label length = address length – index length – block offset length

Some authors refer to block migration simply as “migration” [20] or “displacement”