Cache

A cache is a collection of duplicate data, where the original data is expensive to fetch or
compute (usually in terms of access time) relative to the cache. Future accesses to the
data can be made by accessing the cached copy rather than refetching or recomputing
the original data, so that the perceived average access time is lower. Caches may mark the
cached data as 'stale' when the original data is changed, but this is not always the case
On-Chip Cache Memory (1)
That small amount of memory located on the same chip as the microprocessor is called
On-Chip Cache Memory.
The microprocessor stores a copy of frequently used data and instructions in its cache
memory. When the microprocessor desires to look at a piece of data, it checks in the
cache first. If it is not there, only then the microprocessor asks for the same from the
main memory
On-Chip Cache Memory (2)
L2, cache memory, which is on a separate chip from the microprocessor but faster to
access than regular RAM.
It is the small size and proximity to the microprocessor makes access times short,
resulting in a boost in performance. Microprocessors predict what data will be required
for future calculations and it pre-fetches that data and places it in the cache so that it is
available immediately when the need arises.