Cache Memory

Cache Memory is small and fast memory which is placed between the CPU and main memory.It store data temporary for faster accessible means when you are working on any type of docs. or other document the temporary work get stored in the cache memory that it doesn't have need to access data from primary memory .You asked then what is the need of Primary if temporary data may be accessed by Cache memory.The Cache memory size is not much more than the primary memory that it hold all buffer data..so there is need of primary data.See below example then you figure out what the differences:-