# Making a bootable USB for Mac OS X Mountain lion on Windows 7



## Assass1n

I'm trying to make a bootable USB for Mac OS X Mountain lion on Windows 7.

My Macbook has OS X Lion on it but something happened to it and I can't log in therefore I've been using Windows 7 on it via Bootcamp.

Is there a way to make the bootable USB on Windows 7?

I've already got the Mountain Lion DMG but I've tried numerous methods to open it such as using PowerISO but I get the message "The file format is invalid or unsupported"


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## Elvandil

DMG is not a Windows image format, though some Windows programs can handle them.

But just opening the image and copying to USB will not make a bootable USB. It needs a boot sector installed, too. Do you have directions on how to accomplish what you are doing?


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## Squashman

What seems to be the Login issue?


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## Headrush

Convert the DMG to an ISO and burn.

http://www.winytips.com/burn-dmg-file-on-windows-pc/


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## tompatrick

More Help
http://www.howtogeek.com/102983/how-to-convert-dmg-files-to-iso-files-on-windows/


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## Headrush

tompatrick said:


> More Help
> http://www.howtogeek.com/102983/how-to-convert-dmg-files-to-iso-files-on-windows/


LOL, the link I posted also used DMG2IMG, the difference being you don't have to use it through a command line.

Just try to open the DMG and when it asks which program to use, point to DMG2IMG.


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## Assass1n

When I try open it using UltraISO I get "Invalid or unknown image file format"


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## Assass1n

Tried using the DMG2IMG program but all that happens is that it makes a IMG file that is 0 KB....


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## Headrush

Assass1n said:


> Tried using the DMG2IMG program but all that happens is that it makes a IMG file that is 0 KB....


Did you drop the DMG file onto the DMG2IMG program?

I just tried it and it worked OK.

P.S. I overlooked that part where you mentioned you where trying to put this on a USB stick.
Does you MacBook have an optical drive?


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## sokratus

I am having the same problem. I was upgrading to OS X Mountain Lion from Lion, but something happened and my computer is now stuck at gray screen apple logo spinning wheel. I can surely enter in the recovery mode but I *dont want to delete anything or lose my data*. Now I have other windows computer on which I have downloaded the OS X Lion and I was kinda hoping that *I can create a bootable disk on my windows for my macbook*, so that I can re-install lion. Now I just downloaded the DMG2IMG software and looking online it suggests that I can convert the DMG to ISO, but how will that help in creating a bootable disk or USB (most preferably USB)?


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## sokratus

I got my problem fixed. I downloaded vmware image of Lion on windows. Created a bootable USB of Lion over there. Installed Lion on my mac and mac started to work. Then I created bootable USB on mac for mountain lion. Now everything is working fine.


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