USB Features

Features of the USB ports include the ability to wake the computer out of Sleep mode and the ability to start up the computer from a USB mass-storage device.

Waking Up From Sleep

USB devices can 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 device wakes the computer by sending a Resume event to the USB root hub. The mouse and keyboard that come with the computer use this method to wake the computer on a key press or mouse motion.

This functionality is part of the USB-suspend mode defined in the USB specification. Information about the operation of USB-suspend mode on Macintosh computers is included in the Mac OS USB DDK API Reference, available on the World Wide Web at http://developer.apple.com/documentation/Hardware/DeviceManagers/usb/ usb.html

Booting from USB Storage Devices

The Power Mac G4 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 G4computer includes USB Mass Storage Support 2.0, a class driver that supports devices that meet the USB Mass Storage Class specification.