This firmware update and
related text is from Apple's http://docs.info.apple.com/article.html?artnum=75130
to difficulty downloading from Apple's site I have made it available
This is the 4.1.9 iMac
firmware for slot-load (350 - 700 Mhz) iMacs.
Download the disk image here --->
1.2 MB download
Instructions Carefully before
you begin the install.
About the iMac Firmware Update 4.1.9 ¬
The iMac Firmware Update 4.1.9 will only run on iMac computers
with slot-loading CD or DVD drives running Mac OS 9.1 or later from a
local drive. If you are using Mac OS X you must boot from a local Mac
OS 9.1 or later writeable partition (not a CD, or network disk) prior
to following the update instructions.
Firmware updates are also available for Power Mac G4 and Power
Mac G4 Cube models.
Firmware Update 4.1.9 includes improvements to starting up Mac OS
X from the local hard disk, Firewire target disk mode, starting up from
the local hard disk, network startup, and system stability. This update
also adds support for additional security options which allow the Open
Firmware to be password protected.
Before you install the iMac Firmware Update 4.1.9, read the
instructions below. You may want to print them for reference.
Note: After you install this update, the parameter RAM (PRAM) is
reset. This may reset some of your control panels to default settings.
See Mac Help, available in the Help menu, for more information on
changing your control panel settings.
1. Double-click the iMac Firmware Updater icon.
Note: If a message says your firmware is up-to-date with version
4.1.9 of the iMac Firmware Updater, or that this version of the iMac
Firmware Updater will not run on this computer, then you do not need
this update. If a message says you need to install Mac OS 9.1, the
firmware updater will not run until you install Mac OS 9.1 or later.
2. Follow the onscreen instructions. When prompted, click Shut
Down in the dialog box to shut down your iMac.
3. Locate the programmer's button on the side of the iMac, to the
right of the reset button. Press and
hold in the programmer's button. You may need to use a pen or a
straightened paper clip.
4. While you hold in the programmer's button, press the Power
start up your iMac.
5. Continue to hold in the programmer's button until you hear a
Release the programmer's button when you hear the tone. The
update starts automatically.
A status bar shows the progress of the update. When a message
says your computer's firmware has been successfully updated to version
4.1.9, you are finished.
Note: If a message says the update was not completed
successfully, review the instructions and begin the update process
For more information, see http://www.apple.com/support