How to create a Windows USB installer with Boot Camp on an unsupported Mac

Discussion in 'OS X Mountain Lion (10.8)' started by Manic Harmonic, Nov 12, 2012.

  1. Manic Harmonic macrumors 6502

    Dec 4, 2011
    Here is a simple guide to let boot camp assistant create a USB installer and let you boot from it. I wanted to do this for 2 reasons:
    -My MacBook Pro does not have a DVD drive because I replaced it with a hard drive. The computer will not boot from my superdrive when plugged in through USB (unless it's an OS X installation DVD)
    -A USB installer is much faster than a DVD installer.

    Right now, only certain models, ones that do not come with DVD drives, can create USB drives via Boot Camp Assistant and boot Windows via USB. Basically, all we need to is trick Boot Camp into thinking our computer is one of these supported models.

    Go into Applications/Utilities, control click or right click on Boot Camp Assistant and choose "Show Package Contents." then go to contents/info.plist, and drag it to the desktop. Open it up with TextEdit or even better, a program such as TextWrangler.

    Scroll down a little bit and you should see this: <key>DARequiredROMVersions</key>
    Under that, you should see something like:

    These are the boot ROM versions of all the macs that hav the ability to boot Windows from USB. Copy and paste the first line to the line above it (In most cases, it needs to be on the first line), and delete the section between <string> and </string>. Then, go to system profiler, and check where it says "Boot ROM Version" Copy that text and paste it onto that line between <string> and </string>.

    There's one more thing we nee to do. Scroll down to where it says <key>USBBootSupportedModels</key>
    Under that you should see something like this:


    Copy and paste the top line to the one above it (again, it needs to be the first line). Then delete the area between <string> and </string> on that top line. Go back to your Boot ROM Version in System Profiler. All you need is the first 3 or 4 letters. In my case, those letters were MBP81. On an iMac they would be something like IM122 and on a Mac Pro they would be something like MP51.

    You can now drag the file from the desktop to it's original location. Make sure you have a backup of the file first in case you screwed anything up.

    Now just open up Boot Camp Assistant and you should be able to create a USB drive and be able to boot from it.
  2. joeyboyyy91 Suspended

    Aug 20, 2010
    Can you create the bootable usb from an iso or does it have to be from a physical disk?
  3. PeterHolbrook macrumors 6502a

    Sep 23, 2009
    One of my Macs is an old Mac Pro 1,1 turned 2,1 through flashing and currently running ML 10.8.2 thanks to Chameleon. Even after editing the plist according to the OP's instructions, I receive the message:

    "Boot Camp Assistant cannot be used."
    "You must update your computer's Boot ROM firmware before using this setup assistant."

    And then it kindly invites me to "Quit". Have I done something wrong? What am I missing?

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