Unit - 4
Cache Memory
, Cache Memory - Need Of Cache
The objective of cache memory is to reduce the access time.
Fundamental Idea :
▪ keep the frequently used data and instruction in the cache ,thus reducing
the access time.
▪ When CPU needs to access memory, the cache is searched first for the
data.
▪ If the word is found in the cache , it is accessed from the cache. But if
the word is not in the cache , then access to main memory is done.
▪ And simultaneously word is copied in the cache.
, Cache Memory - Need Of Cache
● The transfer of words from the main memory to cache is done in
blocks.
● A block consists of many words.
● Since cache has small capacity , existing item has to be replaced if
cache is being full. And the replacement is depends upon the
algorithm.
Cache Memory
, Cache Memory - Need Of Cache
The objective of cache memory is to reduce the access time.
Fundamental Idea :
▪ keep the frequently used data and instruction in the cache ,thus reducing
the access time.
▪ When CPU needs to access memory, the cache is searched first for the
data.
▪ If the word is found in the cache , it is accessed from the cache. But if
the word is not in the cache , then access to main memory is done.
▪ And simultaneously word is copied in the cache.
, Cache Memory - Need Of Cache
● The transfer of words from the main memory to cache is done in
blocks.
● A block consists of many words.
● Since cache has small capacity , existing item has to be replaced if
cache is being full. And the replacement is depends upon the
algorithm.
