Use OS X 10.4 on a MacBook that came with 10.5

Aug 13, '08 07:30:00AM

Contributed by: Anonymous

I was able to get Mac OS X 10.4 to run on a new OS X 10.5-based Intel MacBook. To make this work, you need to own an intel iMac or Mac mini that runs on 10.4, as well as a USB hard drive. Here's how I got it working:

  1. Connect the USB disk drive to the iMac or Mac mini.
  2. Run Disk Utility, in the Utilities folder.
  3. Click on the USB disk's icon, then on the Restore tab.
  4. Drag your iMac or Mac mini's disk drive from the left hand column over to the source area.
  5. Drag your USB drive to the destination area.
  6. Check Erase Destination and then click on the Restore button. (This will take a while!)
  7. After this completes, take your USB drive over to your new MacBook.
  8. Remove the battery and remove the screws so that you can take the MacBook's hard drive out.
  9. Plug in your USB drive and power up your new MacBook. It will then boot into 10.4, off the USB drive.
  10. Go to System Preferences and click on Startup disk. Change your startup disk to the USB hard drive and restart your MacBook.
  11. Before you restart your MacBook, and while it is still powered up, plug its internal hard drive back in. [robg adds: The original hint submission was unclear about which disk is being reconnected, and no contact email address was provided. I'm assuming the internal hard drive is the one that needs to be connected, as its currently not in the MacBook.]
  12. After your computer starts up, repeat steps two to six again, but make your source the USB drive and your destination your MacBook's hard drive.
  13. When this completes, you should be able to go to System Preference » Startup Disk, and change your startup disk to your MacBook's hard drive.
Reboot to boot your new MacBook into 10.4 on its internal hard drive.

[robg adds: I have not tested this hint, nor would I recommend it for most users. If you are going to try it, however, I would recommend first cloning (via Carbon Copy Cloner or SuperDuper) the MacBook's 10.5 drive to a separate external drive -- just in case you ever want to easily go back to the existing 10.5 setup.]

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Mac OS X Hints
http://hints.macworld.com/article.php?story=20080731124318425