Difference between Primary and Secondary Memory

Details

What is Memory?

Memory is very much like our brain as it is used to store data and instructions. Computer memory is the storage space where data is to be processed, and instructions needed for processing are stored. The memory is divided into a large number of smaller portions called the cell. Every cell/ location has a unique address and a size.

Two types of memories are:

In this tutorial, you will learn

What is Primary Memory?

Primary memory is the main memory of the computer system. Accessing data from primary memory is faster because it is an internal memory of the computer. The primary memory is most volatile which means data in primary memory does not exist if it is not saved when a power failure occurs.

The primary memory is a semiconductor memory. It is costlier compared with secondary memory. The capacity of primary memory is very much limited and is always smaller compares to secondary memory.

Two types of Primary Memory are:

KEY DIFFERENCE

  • Primary memory is also called internal memory whereas Secondary memory is also known as a Backup memory or Auxiliary memory.
  • Primary memory can be accessed by the data bus whereas Secondary memory is accessed by I/O channels.
  • Primary memory data is directly accessed by the processing unit whereas Secondary memory data cannot be accessed directly by the processor.
  • Primary memory is costlier than secondary memory whereas Secondary memory is cheaper compared to primary memory.
  • Primary memory is both volatile & nonvolatile whereas Secondary memory is always a non-volatile memory.

RAM (Random Access Memory)

Random access memory which is also known as RAM is generally known as a main memory of the computer system. It is called temporary memory or cache memory. The information stored in this type of memory is lost when the power supply to the PC or laptop is switched off.

ROM (Read Only Memory)

It stands for Read Only Memory. ROM is a permanent type of memory. Its content is not lost when the power supply is switched off. The computer manufacturer decides the information of ROM, and it is permanently stored at the time of manufacturing which can not be overwritten by the user.

What is Secondary Memory?

All secondary storage devices which are capable of storing high volume data is referred to secondary memory. It's slower than primary memory. However, it can save a substantial amount of data, in the range of gigabytes to terabytes. This memory is also called backup storage or mass storage media.

Types of Secondary memory

Mass storage devices:

The magnetic disk provides cheap storage and is used for both small and large computer systems.

Two types of magnetic disks are:

Flash/SSD

Solid State Drive provides a persistent flash memory. It's very fast compared to Hard Drives. Frequently found in Mobile phones, its rapidly being adopted in PC/Laptop/Mac.

Optical drives:

This secondary storage device is from which data is read and written with the help of lasers. Optical disks can hold data up to 185TB.

Examples

USB drives:

It is one of the most popular types of secondary storage device available in the market. USB drives are removable, rewritable and are physically very small. The capacity of USB drives is also increasing significantly as today 1TB pen drive is also available in the market.

Magnetic tape:

It is a serial access storage device which allows us to store a very high volume of data. Usually used for backups.

Characteristic of Primary Memory

Characteristic Secondary Memory

Primary Memory Vs Secondary Memory

Parameter Primary memory Secondary memory
Nature The primary memory is categorized as volatile & nonvolatile memories. The secondary memory is always a non-volatile memory.
Alias These memories are also called internal memory. Secondary memory is known as a Backup memory or Additional memory or Auxiliary memory.
Access Data is directly accessed by the processing unit. Data cannot be accessed directly by the processor. It is first copied from secondary memory to primary memory. Only then CPU can access it.
Formation It's a volatile memory meaning data cannot be retained in case of power failure. It's a non-volatile memory so that that data can be retained even after power failure.
Storage It holds data or information that is currently being used by the processing unit. Capacity is usually in 16 to 32 GB It stores a substantial amount of data and information. Capacity is generally from 200GB to terabytes.
Accesses Primary memory can be accessed by the data bus. Secondary memory is accessed by I/O channels.
Expense Primary memory is costlier than secondary memory. Secondary memory is cheaper than primary memory.

Summary

 

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