Mapping function between cache lines and main memory block?

I didn't quite understand your question but I'll answer you anyways :P..

It's known that the main memory is much larger that the cache memory , and we need to transfer a block of instructions to the cache memory to be frequently used by the processor to improve performance and reduce time spent in fetching instructions or data ( dealing with cache memory is much faster than RAM ). for example lets say that a main memory has a 128 data blocks and you need to place them in the cache memory which consists of 32 data blocks? then you have to have sort of technique to place them or MAPPING FUNCTION. And there are plenty of 'em (four mapping techniques as far as i know) i will just mention them without getting into details:

Direct mapping , fully-associative, set-associative and n-way set associative.

if you need more details just ask.

greetings

Can you please provide some help over Direct mapping , fully-associative, set-associative and n-way set associative

Thanx