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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.
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 Connectors.
USB devices connected to the PowerBook computer 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 . That document is part of Apple's USB DDK and is available on the World Wide Web, at:
http://developer.apple.com/documentation/Hardware/DeviceManagers/usb/usb.html
The USB ports on the PowerBook computer comply with the Universal Serial Bus Speci?cation 1.1 Final Draft Revision. The USB controllers comply with the Open Host Controller Interface (OHCI) specification.