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PC Hardware in a Nutshell, Second Edition by Barbara Fritchman Thompson, Robert Bruce Thompson

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Configuring USB

When you are installing new USB devices or troubleshooting existing USB devices, you may need to determine detailed configuration information about your USB interfaces, drivers, hubs, and ports, including the following:

USB Host Controller Interface

It’s frequently necessary to know which USB Host Controller Interface your system uses. For example, the system requirements for a USB peripheral may state that it is incompatible with certain USB HCIs. Also, if you have occasion to troubleshoot a USB problem, knowing which USB HCI your system uses may allow you to pinpoint the problem more quickly, because various USB HCIs have known limitations and incompatibilities.

USB driver information

Although Windows generally installs a suitable USB driver, there are times when upgrading (or downgrading) the default driver is required to allow USB devices to function properly.

USB power information

A USB port provides 500 milliamps of current, which is shared by all devices connected to that port. Connecting several unpowered devices to a port can exceed the maximum allowable current, which may cause problems ranging from sporadic operation to complete failure of all connected devices. Windows allows you to view the total power consumption for each USB port as well as the power consumed by each device connected to that port.

The following sections detail the steps necessary to view and change USB configuration.

Identifying the USB HCI Under Windows 9X

To determine which USB HCI ...

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