Compare the Difference Between Similar Terms

Difference Between

Home / Technology / IT / Systems / Difference Between Primary and Secondary Memory

Difference Between Primary and Secondary Memory

June 21, 2011 Posted by Indika

Primary vs Secondary Memory | Auxiliary Storage Devices

A computer contains a hierarchy of memory devices for storing data. They vary in their capacity, speed and cost. Primary memory (also referred to as the main memory) is the memory that is directly accessed by the CPU to store and retrieve information. Secondary memory (also referred to as the external or auxiliary memory) is a storage device that is not accessible directly by the CPU and used as a permanent storage device that retains data even after the power is turned off.

What is Primary Memory?

Primary memory is the memory that is directly accessed by the CPU to store and retrieve information. Most of the time, primary memory is also referred to as the RAM (Random Access Memory). It is a volatile memory, which loses its data when the power is turned off. Primary memory is directly accessible by the CPU through the address and memory bus and it is constantly accessed by the CPU to get data and instructions. Furthermore, computers contain a ROM (Read Only Memory), which holds instructions that are executed often such as the startup program (BIOS). This is a non volatile memory that retains its data when the power is turned off. Since the main memory is accessed often, it needs to be faster. But they are smaller in size and also costly.

What is Secondary Memory?

Secondary memory is a storage device that is not accessible directly by the CPU and used as a permanent storage device that retains data even after power is turned off. CPU accesses these devices through an input/ output channel and data is first transferred in to the primary memory from the secondary memory before accessing. Usually, hard disk drives and optical storage devices (CDs, DVDs) are used as secondary storage devices in modern computers. In a secondary storage device, data are organized in to files and directories according to a file system. This also allows to associate additional information with data such as the access permissions, owner, last access time, etc. Furthermore, when the primary memory is filled up, secondary memory is used as a temporary storage for keeping least used data in the primary memory. Secondary memory devices are less costly and larger in size. But they have a large access time.

Difference between Primary and Secondary Memory

Primary memory is the memory that is directly accessed by the CPU to store and retrieve information, whereas the secondary memory is not accessible directly by the CPU. Primary memory is accessed using address and data buses by the CPU, while secondary memory is accessed using input/ output channels. Primary memory does not retain data when the power is turned off (volatile) while secondary memory retains data when the power is turned off (non-volatile). Furthermore, primary memory is very fast compared to the secondary memory and has a lower access time. But, primary memory devices are more costly compared to secondary memory devices. Due to this reason, usually a computer comprises of a smaller primary memory and a much larger secondary memory.

Related posts:

Difference Between RAM and ROMDifference Between RAM and ROM Difference Between Static RAM and Dynamic RAM Difference Between Physical and Virtual Memory Difference Between Microprocessor and Microcontroller Difference Between Embedded and External Memory Devices

Filed Under: Systems Tagged With: Auxiliary memory, external memory, hierarchy of memory devices, main memory, permanent storage device, primary memory, Primary vs Auxiliary Storage Devices, RAM, Random Access Memory, Read Only Memory, ROM, Secondary memory, secondary storage devices

About the Author: Indika

Indika, BSc.Eng, MSECE Computer Engineering, PhD. Computer Science, is an Assistant Professor and has research interests in the areas of Bioinformatics, Computational Biology, and Biomedical Natural Language Processing.

Comments

  1. arsala mehr ali says

    January 7, 2012 at 12:48 pm

    is primary or volatile is same?

    Reply
    • smart girl says

      May 4, 2015 at 8:35 am

      Yes its the same

      Reply
  2. arsala mehr ali says

    January 7, 2012 at 12:48 pm

    ply fast guyz

    Reply
  3. arsala mehr ali says

    January 7, 2012 at 1:37 pm

    is storage or memory is same?

    Reply
    • smart girl says

      May 4, 2015 at 8:34 am

      Yes

      Reply
  4. p.gnanika says

    December 19, 2017 at 6:23 pm

    is secondary memory is ROM???

    Reply
  5. shahzad ali raja says

    January 29, 2019 at 6:09 am

    primary memory is volatile and rom is a part of primary memory(non volatile). what is difference between this

    Reply

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Request Article

Featured Posts

Difference Between Coronavirus and Cold Symptoms

Difference Between Coronavirus and Cold Symptoms

Difference Between Coronavirus and SARS

Difference Between Coronavirus and SARS

Difference Between Coronavirus and Influenza

Difference Between Coronavirus and Influenza

Difference Between Coronavirus and Covid 19

Difference Between Coronavirus and Covid 19

You May Like

What is the Difference Between Diffuse and Centralized Nervous System

What is the Difference Between Diffuse and Centralized Nervous System

Difference Between Thalamus and Hypothalamus

Difference Between Benzonase and DNase

Difference Between Benzonase and DNase

Difference Between Nitrogen and Nitrate

Difference Between Nitrogen and Nitrate

Difference Between Options and Swaps

Difference Between Options and Swaps

Latest Posts

  • What is the Difference Between Calcitriol and Cholecalciferol
  • What is the Difference Between Protein C and Protein S Deficiency
  • What is the Difference Between Raynaud’s Syndrome and Raynaud’s Phenomenon
  • What is the Difference Between Magnesium Citrate Malate and Glycinate
  • What is the Difference Between Appendicitis and Ovarian Cyst
  • What is the Difference Between PAD and Venous Insufficiency
  • Home
  • Vacancies
  • About
  • Request Article
  • Contact Us

Copyright © 2010-2018 Difference Between. All rights reserved. Terms of Use and Privacy Policy: Legal.