Cache Memory
The cache memory exists between microprocessor (CPU) and main memory. It is faster than main memory. Its access time is around 10 nanoseconds. It stores data and instructions which are to be immediately executed. It is more expensive and smaller than main memory.
Cache hit and miss
When the CPU requires data or instructions while processing, it looks into cache memory first. If the information exists then it is called cache hit; otherwise it is called cache miss and the information will be retrieved from main memory. If the number of cache hits exceeded number of misses then the system performance is assured.
Cache Controller
The cache controller is a circuit in the motherboard. It decides the content of the cache. The controller uses the recently accessed data or instructions to infer the RAM locations that may be accessed next.