Difference Between Primary and Secondary Memory

Key Difference between Primary Memory and Secondary Memory

• 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.
• Comparing primary and secondary storage devices, Primary storage devices are costlier than secondary storage devices, whereas Secondary storage devices are cheaper compared to a primary storage devices.
• When we differentiate primary and secondary memory, Primary memory is both volatile & nonvolatile, whereas Secondary memory is always a non-volatile memory.

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:

• RAM
• ROM

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:

• Floppy disks
• Hard disks

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

• CD
• DVD
• Blue Ray

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.

Difference Between Primary and Secondary Memory

Here is the difference between Primary and 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.

Characteristics of Primary Memory

• The computer can’t run without primary memory
• It is known as the main memory.
• You can lose data in case power is switched off
• It is also known as volatile memory
• It is a working memory of the computer.
• Primary memory is faster compares to secondary memory.

Characteristics of Secondary Memory

• These are magnetic and optical memories
• Secondary memory is known as a backup memory
• It is a non-volatile type of memory
• Data is stored permanently even when the power of the computer is switched off
• It helps store data in a computer
• The machine can run without secondary memory
• Slower than primary memory

Summary

• Computer memory is the storage space where data is to be processed, and instructions needed for processing are stored
• Two types of memories are: Primary memory and Secondary 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.
• All secondary storage devices which are capable of storing high volume data is referred to as secondary memory
• Types of Primary Memory 1) RAM, 2) ROM
• Types of Secondary Memory 1) Hard Drive, 2) SSD, 3) Flash, 4) Optical Drive, 5) USD Drive, 3) Magnetic Tapes
• The computer can’t run without primary memory. You can lose data in case power is switched off
• Data is stored permanently in Secondary Memory even when the power of the computer is switched off
• Primary memory is expensive and is available in limited in size in a computer.
• Secondary memory is cheaper compared to primary memory.