Memory is a solid state digital device where it provides storage for data values. It’s also known as memory cell which exhibit two stable states represented by binary digit 1’s and 0’s.

      So what we the ‘users’ usually want in a memory is that it has a huge storage capacity and fast so that everything is kept within instant access whenever we want it. Well fortunately we can achieve that now by using a method known as “Memory Hierarchy”.

Reading Ahead

        The concept is to reduce the data access time so that we can obtain data needed very very fast. To do that we use a technique called “ reading ahead ”.

        We can imagine the concept of “ reading ahead ”through the flow of a simple diagram. Below is an example of such diagram and its explanation.

Step 1: The CPU will go to cache and check if it can retrieve data from there.

Step 2: When there is no data at the cache, the CPU will go to RAM next and retrieve one part of
             the data from there.

Step 3: The cache control works by retrieving other parts of the data needed by the CPU and
             moving them to the cache.

Step 4: The data is passed to the cache.

Step 5: Now the CPU will once again go to cache and try to retrieve data from there.

Step 6: The other parts of the data needed by the CPU is retrieve from cache without needing to
             go to RAM and thus, shortening the data access time.

Virtual Memory

        Virtual memories are fake memories where the computer uses a process called “swap space” to make as if the memory appears to have a larger capacity. Swap space works through the concept of when there is no more memory space left in your RAM, it will swap some memory space with the secondary memory.

There are 2 types of memory which are:

(a) Volatile memory (RAM)

(b) Non-volatile memory (Flash Memory, Optical Disk, Magnetic Disk)

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