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 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.
Compared to primary and secondary storage devices, primary storage devices are costlier than secondary storage devices, whereas secondary storage devices are cheaper.
When we differentiate between primary and secondary memory, Primary memory is both volatile and non-volatile, whereas Secondary memory is always a non-volatile memory.

Here, I have analyzed the difference between Primary Memory and Secondary Memory and will comprehensively evaluate their pros and cons.

What is Primary Memory?

Primary Memory is the main memory of the computer system. Accessing data from primary memory is faster because it is the computer’s internal memory. The primary memory is the most volatile, meaning data in the 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 limited and is always smaller compared to secondary memory.

Two types of Primary Memory are:

RAM (Random Access Memory)

Random access memory also known as RAM is generally known as the 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.

Also, read our article comparison between RAM and ROM.

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 persistent flash memory. It’s very fast compared to Hard Drives. Frequently found in Mobile phones, it is rapidly being adopted on PCs, laptops, and Macs.

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 devices available in the market. USB drives are removable, rewritable, and physically very small. The capacity of USB drives is also increasing significantly, and today, a 1TB pen drive is also available on the market.

Magnetic tape:

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

Difference Between Primary Memory and Secondary Memory

Based on my experience, here is how I distinguish between Primary and Secondary memory:

Parameter	Primary Memory	Secondary Memory
Nature	The primary memory is categorized as volatile and non-volatile memories.	The secondary memory is always a non-volatile memory.
Alias	These memories are also called internal memory.	Secondary memory is known as backup memory, 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 can CPU access it.
Formation	It’s a volatile memory, meaning data cannot be retained in the event of a power failure.	It’s a non-volatile memory so 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 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.

Features of Primary Memory

In my experience, these are the features of primary memory.

Directly accessible by the CPU
Volatile nature results in data loss upon power shutdown.
It comprises both RAM (Random Access Memory) and ROM (Read-Only Memory)
Essential for the execution of running applications
Limited in capacity compared to secondary storage
Higher cost per bit than secondary memory
Crucial for system boot-up and operating system functionality

Features of Secondary Memory

In my extensive use, I have noted these features of secondary memory.

Capable of storing large volumes of data affordably.
Easily removable and portable, it enables data transfer between devices.
Typically used for backup to safeguard against data loss
It can be accessed sequentially or randomly, depending on the technology used.
Available in various forms such as SSDs, HDDs, tapes, and optical discs
It requires longer access times than volatile memory types.
Often designed for durability to withstand long-term use and environmental factors.

Characteristics of Primary Memory

The computer can’t run without primary memory.
It is known as the main memory.
You can lose data if the power is switched off.
It is also known as volatile memory.
It is the working memory of the computer.
Primary memory is faster compared 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 on a computer.
The machine can run without secondary memory.
Slower than primary memory

How to Choose Between Primary Memory and Secondary Memory

In managing data processing, I depend on computer memory to serve as the storage area for data and for retaining the needed instructions.
Two types of memories are: 1) Primary memory and 2) Secondary memory
Primary memory is the main memory of the computer system. Accessing data from primary memory is faster because it is the computer’s internal memory.
All secondary storage devices that are capable of storing high volumes of data are 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 if the power is switched off.
Data is stored permanently in secondary memory even when the computer’s power is switched off.
Primary memory is expensive and is limited in size in a computer.
Secondary memory is cheaper compared to primary memory.

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