Click the link for Mac OS X on http://www.dosbox.com/download.php?main=1
For those of you new to Mac:
-A .dmg is a compressed disk image that OS X can decompress and run like a CD-ROM.
-An universal binary is something that runs on both PowerPC and Intel processors. If you bought your Mac after 2006, you most likely have an Intel processor.
If the image does not open automatically (in Safari, it typically will), go to where you downloaded the image, and double-click on it. It will mount, and a new window called "DOSBox 0.74" will pop-up.
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Next important step: create a folder to use as virtual C:\ in DOSBox.
Go to Macintosh HD, Users, <YourName>. Here, create a new folder called "DOS."
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Go back to your Applications folder. Start the app. Then close it! By doing this, you will propagate a preference file you can edit.
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Now, go to your Home folder ("/Users/<YourName>"), and click on Library. Go to Preferences, and find the file that says DOSBox 0.74 Preferences.
Right click (or hold down the control key and click), and open the file with TextEdit.
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Scroll the whole way down to header [autoexec] and add:
mount c "/Users/<YourName>/DOS"
c:
Save and exit.
Run DOSBox now. If you did it all correctly, DOSBox will start up with a C:\ prompt ready.
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Using a virtual C located in your personal folders will avoid getting all kind of troubles installing/saving games running in DOSBox.
Now get out there and play some DOS games!!