I recently had to upgrade my Mac Mini from OSX 10.4.x (Tiger) to OS X 10.5 (Leopard.)

In order to do so, I had to figure out how to make my Mac boot up from the CD/DVD drive, not from the hard disk.

Here are few different methods for booting from CD on a Mac:

  • Restart your computer and immediately press the c key. The computer will look for a bootable CD or DVD and, if it finds one, will use it as its startup device.
  • Restart your computer and immediately press Cmd-Option-Shift-Delete.
  • Restart your computer and immediately press the Option key. Icons for all available startup volumes will appear. Click the one you want to boot from.