Understanding Virtual Memory

Written by Barry Dysert (last updated November 23, 2020)

Virtual memory is the name given to the contiguous address range used by a computer program. For a program to run, its instructions must reside in physical memory. However, when there are several programs running simultaneously or when there's not enough physical memory to encompass the amount of memory needed by a program, the computer uses virtual memory to fulfill the program's needs.

For example, if two programs are running at the same time, each program treats memory as if it's one large contiguous block beginning at address zero and extending as far as necessary. Since each program can't access the memory at physical address zero simultaneously, the computer creates blocks (address ranges) of virtual memory that make it seem to each program that it has all of the computer's memory to itself.

Virtual memory is also used when programs need more memory than physically exists in the computer. The computer uses a process called paging to allow programs to access more memory than physically exists. Through paging, the computer keeps track of what blocks of physical memory are currently available, writes the contents of those blocks to disk, and then reads in from disk the previously written data that the currently executing program needs. By using the disk as a temporary storage medium, many different programs can be running at the same time and accessing large portions of memory without ever having to be concerned with whether the data is physically in memory at the time or needs to be paged in from disk.

 This tip (12623) applies to Windows 7, 8, and 10.

Author Bio

Barry Dysert

Barry has been a computer professional for over 35 years, working in different positions such as technical team leader, project manager, and software developer. He is currently a software engineer with an emphasis on developing custom applications under Microsoft Windows. When not working with Windows or writing Tips, Barry is an amateur writer. His first non-fiction book is titled "A Chronological Commentary of Revelation." ...

MORE FROM BARRY

Creating a Disk Partition

Partitioning your disk offers a quick and efficient means to make good use of your disk resources. By creating disk ...

Discover More

Customizing the Explorer's File List Display

Windows Explorer is a powerful utility to use for navigating among your files and folders. And it can be customized a ...

Discover More

Using Windows Easy Transfer

If you ever want to copy user accounts, documents, pictures, etc., from one computer to another, you'll find that Windows ...

Discover More
More WindowsTips

Removing Spyware with Windows Defender

Despite your best efforts, it's possible that your system might still get afflicted with spyware. If that happens, you ...

Discover More

Wielding the Power

If you are done using Windows for a while, it is a good idea to shut down your system. Windows provides several different ...

Discover More

Disabling Startup Apps

As your computer starts up, certain apps may be causing your system to run or startup slowly. A quick check of your ...

Discover More
Comments

If you would like to add an image to your comment (not an avatar, but an image to help in making the point of your comment), include the characters [{fig}] (all 7 characters, in the sequence shown) in your comment text. You’ll be prompted to upload your image when you submit the comment. Maximum image size is 6Mpixels. Images larger than 600px wide or 1000px tall will be reduced. Up to three images may be included in a comment. All images are subject to review. Commenting privileges may be curtailed if inappropriate images are posted.

What is 3 + 1?

There are currently no comments for this tip. (Be the first to leave your comment—just use the simple form above!)

Newest Tips
Links and Sharing
OUR COMPANY
OUR PRODUCTS
OUR SITES
 

Copyright © 2025 Sharon Parq Associates, Inc.