PATHDocumentation > Hardware > Power Mac G4 Cube Developer Note

     

USB Interface

The KeyLargo IC implements two independent USB controllers (root hubs), each of which is connected to one of the ports on the back panel of the computer. The use of two independent controllers allows both USB ports to support high data rate devices at the same time with no degradation of their performance. If a user connects a high-speed (12 Mbps) device to one port and another high-speed device to the other, both devices can operate at their full data rates.

USB port 2 (the connector closest to the FireWire connectors) is also connected to the USB pins on the ADC connector. USB devices connected to an ADC monitor share the root hub with USB port 2.

The two external USB connectors support USB devices with data transfer rates of 1.5 Mbps or 12 Mbps. For more information about the connectors, see USB Ports.

USB devices connected to the Power Mac G4 Cube are required to support USB-suspend mode as 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 . To obtain that document or Apple's USB DDK, see the references shown in USB Interface.

The USB ports on the Power Mac G4 Cube comply with the Universal Serial Bus Specification 1.1 Final Draft Revision. The USB controllers comply with the Open Host Controller Interface (OHCI) specification.


© 2000 Apple Computer, Inc. (Last Updated 04 Oct 00)