Features of the USB ports include power saving modes and the ability to start up the computer from an USB mass-storage device.
The KeyLargo IC sends a signal to the computer to wake from Sleep mode on connect, disconnect, and resume events from compatible USB devices that support the USB-suspend mode. Information about the operation of USB-suspend mode on Macintosh computers is included in the Mac OS USB DDK API Reference . To obtain that document or Apple's USB DDK, see the references shown in USB Interface.
USB devices can also provide a remote wakeup function for the computer. The USB root hub in the computer is set to support remote wakeup whenever a device is attached to or disconnected from the bus. The mouse and keyboard that come with the computer use this method to wake the computer on a key press or mouse motion.
The Power Mac G4 Cube computer can boot from a USB storage device that follows the USB Mass Storage Class specification.
Class drivers are software components that are able to communicate with many USB devices of a particular kind. If the appropriate class driver is present, any number of compliant devices can be plugged in and start working immediately without the need to install additional software. The Mac OS for the Power Mac G4 Cube includes USB Mass Storage Support 2.0, a class driver that supports devices that meet the USB Mass Storage Class specification.
The Power Mac G4 Cube uses an Open Host Controller Interface (OHCI) controller for USB communication. Some early USB devices (most notably keyboards) can't interoperate with an OHCI controller. Those devices are not supported by the Macintosh USB system software.