MEMORY HEIRARCHY AND ITS NEED

ITS TYPES ARE : 

1. INTERNAL MEMORY :                  (i) Registers : fastest possible access(1 cpu cycle) . Its type is given below

(ii) Cache memory :

Level 1 (L1) Cache

It is also called primary or internal cache. It is built directly into the processor chip. It has small capacity from 8 Km to 128 Kb.

Level 2 (L2) Cache

It is slower than L1 cache. Its storage capacity is more, i-e. From 64 Kb to 16 MB. The current processors contain advanced transfer cache on processor chip that is a type of L2 cache. The common size of this cache is from 512 kb to 8 Mb.

Level 3 (L3) Cache

This cache is separate from processor chip on the motherboard. It exists on the computer that uses L2 advanced transfer cache. It is slower than L1 and L2 cache. The personal computer often has up to 8 MB of L3 cache.

2. MAIN MEMORY : also known as primary storage.RAM

                size : in Gb's     best access speed : 10gb/sec

3.DISK STORAGE : also known as secondary storage.HARD DISK,ETC

                size : in Tb's     best access speed : 600mb/ sec(in case of solid state drive)

4.NEARLINE OR EXPANDABLE STORAGE : PENDRIVE,  EXTERNAL HARD DISK,ETC

           size : depending upon hardware   best access speed : 160mb/sec

5.ONLINE STORAGE : it is not immediately available but it requires some human intervention to bring online.LIKE cloud storage.

why we need different types of memory  ?

1. main motive is to use different devices in best optimized way

2. also to reduce speed mismatch among high & low speed memory.

3.to provide less costly of diff speed memories  combination for customers

4. for different types of hardware support.