DMG
(Disk iMaGe) The file format used in the Macintosh for distributing Mac software. Mac install packages appear as a virtual disk drive on the Mac as if you had inserted a CD or floppy disk. When you double click the DMG file icon, the virtual drive is "mounted" on the desktop.
From the Days of Floppies
The DMG format harks back to the days when the Mac was a floppy-only machine. DMGs enabled data to be written to multiple floppy disks without having to keep inserting and removing them. It was also a handy way of making multiple copies of a floppy. Before the computer was turned off, the data had to be saved to the hard disk or to physical floppy disks.
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| Mounting a DMG |
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| This Toast software installation downloads from the Internet as a DMG file. When double clicked, it is "mounted," and the dialog box opens to start the installation by dragging the icon on the left to the icon on the right. |