Apple has released separate firmware updates for slot-loading iMacs, iBooks, Power Mac G4s, and FireWire-equipped PowerBooks running Mac OS 9.0 or later. The patches update the firmware to version 2.4, and address the following issues:
Slot-loading iMacs can better handle AC power fluctuations that might cause the machine to shut down unexpectedly, and those running Mac OS 9.0.4 gain the capability of using a FireWire device as a startup disk. The update also fixes uncommon problems where the machine may not start up correctly.
iBooks gain improved support for 256 MB memory modules and USB storage devices.
On Power Mac G4s, the update corrects problems recognizing more than 1 GB of memory and startup problems with some third-party memory modules. Also, early Power Mac G4s gain the capability to use a FireWire device as a startup disk.
FireWire-equipped PowerBooks also gain improved support for USB storage devices and the ability to use a FireWire device as a startup disk. The update also improves support for FireWire target disk mode, which enables the PowerBook to be connected to another Mac as if it were an FireWire drive.
All the updates are available as self-mounting disk images and are less than 700K downloads. Before performing any firmware update, be sure to read the instructions with the update for complete information on upgrading your firmware - and having a complete backup of your data in case something goes wrong is never a bad idea. However, remember that Apple's firmware upgrades are irreversible and sometimes cause problems for third party add-ons such as SCSI PCI cards. If you use such peripherals, we'd encourage you to check with the vendor before updating.