WINDOWS 1002000 PROFESSIONAL RESOURCE KIT [Electronic resources] نسخه متنی

Device Tree

The Windows 2000 Professional device tree is a record of the devices currently loaded, based on the configuration information in the registry. The device tree is created in random access memory (RAM) each time the system is started or whenever a dynamic change occurs to the system configuration.

Each branch in the tree defines a device node with the following requirements for system configuration:

Unique identification code, or device ID.

List of required resources, such as interrupt request (IRQ) and memory range, including resource type.

List of allocated resources.

Indication that the device node is a bus, if applicable (each bus device has additional device nodes under it in the tree).

Most information in the device tree can be accessed through Device Manager, shown in Figure 19.1. Device Manager contains a representation of the active device tree, listing the system device nodes. Under each node are listed the actual devices configured for your system; double-clicking a device node exposes its device list. You can use Device Manager to install or uninstall devices, troubleshoot problems with devices, update drivers, and change the resources that are assigned to devices.

For more information about using Device Manager to configure devices, see "Configuring Device Settings" later in this chapter.

NOTE

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You can also see the information in the device tree in the registry. For more information about the registry, see the Technical Reference to the Windows 2000 Registry (Regentry.chm) on the Microsoft® Windows® 2000 Resource Kit companion CD.

Figure 19.1 Device Manager

Viewing Hidden Devices

Device Manager does not display all devices by default. Non–Plug and Play devices and certain other devices are hidden. At times, you might need to view these hidden devices for troubleshooting problems with devices installed on your computer.

To view hidden devices

In device manager, click the View menu, and then select Show hidden devices.

In addition to hiding non–Plug and Play devices, Device Manager also hides phantom devices. These are devices which are not currently attached to the computer.

To view phantom devices

At the command prompt, type:

set DEVMGR_SHOW_NONPRESENT_DEVICES=1

Start Device Manager.

From the command prompt, type:

start devmgmt.msc

You can now troubleshoot problems with hidden devices. For more information about troubleshooting device problems, see "Troubleshooting Device Management" later in this chapter and "Troubleshooting Tools and Strategies" in this book.

NOTE

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You can set Device Manager to always show phantom devices. In Control Panel, double-click System, click the Advanced tab, and then in the Environment Variables dialog box, create the variable set DEVMGR_SHOW_NONPRESENT_DEVICES=1.