I have a Fat32 USB that I would like to boot on my iMac 4,1.

The Mac does not recognize the device from the boot menu (option key on boot) and I have tried the Plop disk but it freezes when it says loading boot sector.

How can I get this USB to boot?

  • Are you using Boot Camp?
    – dwightk
    Apr 23 '14 at 16:23
  • 1
    What does this have to do with booting from USB? For this issue I am trying to start a custom live CD. Which works on other computers... Apr 23 '14 at 17:53

You need to use Disk Utility or a 3rd Party App designed to create Bootable Disks. If using Disk Utility, you need to follow some steps to create a Boot Disk, and use the proper format (which is not FAT32 for a Mac). You should be using the HFS+ format (Mac OS Extended Journaled), and there are some additional steps you need to take to make the disk "bootable".

Cult of Mac has an excellent article on this:


FAT32 is good for having a drive that can be read/written from a PC or Mac, but you cannot boot a Mac from that format.

  • Thanks! I was eventually able to get it to boot. I used plop to force USB 1.1 in mode 2. Unfortunately I was not able to use my keyboard prior to the live coding starting. Apr 23 '14 at 17:55

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