Explain Cache Memory With Example

• If the active portions of the program and data are placed in a fast small memory, the average memory access time can be reduced.
• Thus reducing the total execution time of the program.
• Such a fast small memory is referred to as cache memory.
• The cache is the fastest component in the memory hierarchy and approaches the speed of CPU component.
• When CPU needs to access memory, the cache is examined.
• If the word is found in the cache, it is read from the fast memory.
• If the word addressed by the CPU is not found in the cache, the main memory is accessed to read the word.
• The basic characteristic of cache memory is its fast access time.
• Therefore, very little or no time must be wasted when searching the words in the cache.
• The transformation of data from main memory to cache memory is referred to as a 
  mapping process, there are three types of mapping:
  n Associative mapping

  n Direct mapping

  n Set-associative mapping

  
  
• To help understand the mapping procedure, we have the following example: