To upgrade your iMac’s firmware, read through the instructions below. (You may want to print them.) When you’re ready, click Shut Down.

1.  Click Shut Down to shut down your iMac.

2.  Open the port cover door on the side of your iMac and insert the end of a straightened paper clip into the Programmer’s button hole, the lower of the two button holes. (For more information, see the online documentation for your iMac.)

3.  Continue to hold the paper clip in the hole and press the Power button on your iMac or on the Apple USB keyboard to start up your iMac.

4.  When you hear a long tone, remove the paper clip.  A progress bar will appear at the bottom of the screen as the update takes place.

5.  After your iMac starts up, the PRAM is reset and you may need to reset some of your iMac preferences.  (For more information, see Mac OS Help.)