What Is DMG?

You may have come across the file extension "DMG" in your Internet surfing and been frustrated by your inability to open it on your PC. As with many computer programs, a DMG file (or disk image file) is created by a specific operating system used by Macintosh computers. Knowing what it is and, more importantly, how to open it on a Windows-based computer can save you a lot of trouble and headache.

Use of DMG

DMG files are created for distribution among Apple Mac users. A DMG acts as a "virtual" hard drive or disk drive containing discrete copies of files and other information, as if another hard drive or disk drive were installed on the computer. This virtual hard drive can then be "mounted" on a CD or flash drive and shared between computers.

Requirements

DMG is specific to Mac OS X but can be used in non-Mac computers running Windows XP or Windows Vista if a conversion application (also called a "tool") is used. Older versions of Mac OS (such as Mac OS 9) cannot open these files, nor can earlier versions of Windows even with a converter tool.

Opening a DMG

Opening a DMG file is easy; merely double-clicking the icon will "mount" it, making it ready to use. With Windows XP, you must run the conversion tool first, specifying the file to be opened and following the on-screen prompts.

Creating a DMG

To create a new DMG folder, you will need to create a regular file folder and place files in it. Then hold "Ctrl" while clicking the folder and select "Get Info" and note the size of its contents. Then open your Disk Utility (select Applications, then Utilities, then Disk Utility) and click the "New Image" icon to create a new disk image (DMG). Choose a name for your new DMG and select an appropriate size for the folder you made. Set the encryption to "none" and Format to "read/write disk image" or "DVD/CD Master." Finally, place the contents of the folder into the newly mounted disk image.

Warnings

DMG files were not intended to be opened on Windows-based computers, and, despite using reliable software, you may encounter some problems when opening the file. Usually this is because there is an error in your computer's registry; running a registry scan will pinpoint some errors that may prevent you from opening a DMG file. If the file will still not open, the information it contains may be corrupt and you may need to get another copy of it.

References

• File Extension DMG Information
• MacUsers: DMG Files in Older Operating Systems
• DMG Opening Tool for Windows XP