Technical Reference Guide www.hp.com 5-25
Input/Output Interfaces
5.7 Universal Serial Bus Interface
The Universal Serial Bus (USB) interface provides asynchronous/isochronous data transfers with
compatible peripherals such as keyboards, printers, or modems. This high-speed interface
supports hot-plugging of compatible devices, making possible system configuration changes
without powering down or even rebooting systems.
As shown in Figure 5-8, the USB interface is provided by the 82801 component. All systems
provide as total of eight USB ports, two USB ports accessible at the front of the unit and six USB
ports on the rear panel. The USB ports are dynamically configured to either a USB 1.1 controller
or the USB 2.0 controller depending on the capability of the peripheral device. The 1.1
controllers provide a maximum transfer rate of 12 Mb/s while the 2.0 controller provides a
maximum transfer rate of 480 Mb/s.
Figure 5-8. USB I/F, Block Diagram
82801 ICH8
USB 1.1
Front Panel
Rear Panel
Cntlr. #1
USB 1.1
Cntlr. #2
USB 1.1
Cntlr. #3
USB 1.1
Cntlr. #4
USB 2.0
Cntlr.
1.1 0
1.1 1
1.1 2
1.1 3
1.1 4
1.1 5
1.1 6
1.1 7
Data 0
USB Port 1
2.0 0
2.0 1
2.0 2
2.0 3
2.0 4
2.0 5
2.0 6
2.0 7
Data 1
Data 2
Data 3
Data 4
Data 5
Data 6
Data 7
USB Port 2
USB Port 3
USB Port 4
USB Port 5
USB Port 6
USB Port 7
USB Port 8
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