iMac: How to Install an iMac Firmware Update

The following instructions are included in the Read Me files for all iMac Firmware Updates.

Note: After you upgrade the firmware, the PRAM is reset and you may need to reset some of your iMac preferences. For example, you may need to reselect your startup disk from the Startup Disk Control Panel. For more information, see Mac OS Help.

The following instructions are included in the Read Me file for all iMac Firmware Updates. Some iMac models require the use of a straightened paper clip or other similar object to reach the interrupt button, located in the connector recess area on the right hand side of the iMac.

This article has been archived and is no longer updated by Apple.
    1. Double-click the iMac Firmware Updater icon to start the update.
    2. Read the onscreen instructions and follow them carefully.
    3. On a /A configuration, a message will appear explaining that your iMac's firmware needs to be updated.


    4. On all other configurations, a message will appear saying you need to shut down your computer and insert the end of a straightened paper clip into the Programmer's button hole, follow steps 5 through 9 to complete the update process.
    5. Click Shut Down in the dialog box to shut down your computer.
    6. Open the port cover door on the right 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.
    7. Continue to hold the paper clip in the hole and press and release the Power button on your iMac or on the Apple USB keyboard to start up your iMac.
    8. 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.
    9. After your iMac starts up, if the update process was successful, a message appears saying the firmware is up-to-date. Click OK.


If a message appears saying the update was not completed successfully, go back to step 1 and begin the update process again.

Error Checking Prior to the Installation

A number of conditions are required before a firmware update can be performed. Failure to meet these conditions will result in a number of error conditions and the resulting dialogs will be shown on the screen.

  • If the updater file has been moved outside of the folder containing the update installer.
  • If the updater is used on a computer other than an iMac
  • If a Mac OS error #123 occurs
  • If the volume is locked
  • If the firmware is not recognized
  • If the hard disk is out of space


If the iMac Firmware 3.0 Updater file can not be found, the following dialog message will be seen. To user has the option to search for the update file or to cancel the updater.




If the iMac Firmware Updater is used on a computer other than an iMac, the following dialog will result.




If a Mac OS error occurs, the following dialog will result. This is a generic placeholder error dialog message reserved for any Mac OS error messages.




If the volume that is being updated is locked, the following dialog will result. (The most common reason for a locked volume is when you start up from a CD. Make sure you start up from your hard disk drive.)




If the firmware on the iMac is not recognized, the update will not be performed and the following update will result.




If the Macintosh HD is out of space, the update will not be performed and return the following result. There should be approximate 2.5 MB of space available on the hard drive for the firmware update to install properly.




Conditions that May Cause the iMac Firmware Updater to not work

There are other conditions that may cause the updater to not work.

  • If power is removed during the update, the Boot ROM may become corrupted and not retrievable.
  • If a /A configuration is restarted using the paper clip by mistake, the update will not complete. Power must be pulled for 15 seconds and the update attempted again.

Note: The Open Firmware command line is not used in this firmware update process. Any attempts to update an iMac's firmware using the command line mode may lead to BOOT ROM corruption. Modifications of iMac's open firmware using the command line mode is not supported and any resulting damage to the processor board may not be covered under warranty.

How to Determine If a System Has Already Been Updated

The Firmware Update installer will verify that the update is required before installing it and will display a dialog if the update is not required. If you are unsure if your computer has been updated you can simply run the Update installer. If the firmware has been updated, the installer will tell you.

You can also use the Apple System Profiler version 2.1.2 or later to determine the currently installed boot ROM version. After starting Apple System Profiler, click the "System Profile" tab, then click the disclosure triangle next to "Production Information".

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