Computer Memory Notes for IBPS Bank Exam - A memory of computer is just like a human brain.It is used to store data and instructions. Computer memory is the storage space where data is to be processed and instructions after processed are stored. The memory is divided into large number of small parts called cells .each cell has a unique address which varies 0 to memory size minus one.
Types of Computer’s Memory
Memory is three types
- Primary Memory
- Secondary memory
- Cache memory
Primary Memory (Main memory)
Primary memory holds only those data and instructions on which computer is currently working. It has limited capacity and data is lost when power is switched off. It is generally made up of semiconductor device. These memories are not as fast as registers. The data and instruction required to be processed reside in main memory. It is divided into two subcategories RAM and ROM.
Characteristics of Main Memory
- These are semiconductor memories
- It is known as main memory.
- Usually volatile memory.
- Data is lost in case power is switched off.
- It is working memory of the computer.
- Faster than secondary memories.
- A computer cannot run without primary memory.
This type of memory is also known as external memory or non-volatile. It is slower than main memory. These are used for storing data/Information permanently. CPU directly does not access these memories instead they are accessed via input-output routines. Contents of secondary memories are first transferred to main memory, and then CPU can access it.
Characteristic of Secondary Memory
- These are magnetic and optical memories
- It is known as backup memory.
- It is non-volatile memory.
- Data is permanently stored even if power is switched off.
- It is used for storage of data in a computer.
- Computer may run without secondary memory.
- Slower than primary memories.
Cache memory is a very high speed semiconductor memory which can speed up CPU. It acts as a buffer between the CPU and main memory. It is used to hold those parts of data and program which are most frequently used by CPU. The parts of data and programs are transferred from disk to cache memory by operating system, from where CPU can access them.
Advantages & Disadvantages of Cache memory
- The advantages of cache memory are as follows:
- Cache memory is faster than main memory.
- It consumes less access time as compared to main memory.
- It stores the program that can be executed within a short period of time.
- It stores data for temporary use.
- The disadvantages of cache memory are as follows:
- Cache memory has limited capacity.
- It is very expensive.