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Tip Internal ISDN adapters show up in Device Manager under the Network Adapters category. External ones appear in the Modems category.
Multilink dialing means that you can combine two communications devices to act as a single 'virtual' channel. Windows XP Professional supports multilink setups with ISDN and analog modem lines, with the caveat that the server side of the connection must support them, too. That is, if you're connecting to the Internet, for example, your ISP (Internet Service Provider) must support multilink access, and some don't.
You set up multilink connections in the Network Connections folder, on a connection-by-connection basis. Chapter 13 provides the details. It's not necessary to do anything special in Device Manager other than make sure both devices (ISDN adapter, two modems, whatever) are properly installed.
I/O Hardware Configuration Tips
This section contains small bits of wisdom on Device Manager, interrupt sharing, a Plug and Play wrinkle, and mouse configuration.
Microsoft uses Device Mangler (oops, that's 'Manager') for all those hardware configuration details that don't appear in any control panel. The Device Manager display (see Figure 8-5) has been around for a long time in the Windows 9x environment but it's a relatively new (and welcome) addition to the NT platform.
Figure 8-5: The Device Manager window goes beyond the Control Panel.
Get to the Device Manager in a variety of ways, including:
* Choose Start?Control Panel, choose the System control panel (assuming you're using the 'classic' view), click the Hardware tab, and click the Device Manager button.
* Right-click My Computer, choose Properties, click the Hardware tab, and click the Device Manager button.
* Right-click My Computer, choose Manage, and click the Device Manager icon in the left window.
The general procedure is to expand the tree by clicking the + sign next to the device category of interest. Then, right-click the device you want to configure and choose Properties. What you see at that point varies from device to device.
Device Manager errors
Device Manager communicates errors three ways:
* A yellow exclamation point icon next to a device name means the device's driver is wrong, configured improperly, or missing.
* A red 'stop' icon next to a device name means either you or Windows XP has disabled the device.
* A yellow question mark means Windows XP knows that something is there, but doesn't know what it is or which driver to assign it.
In any of these three cases, the device doesn't work right, and you must give its property sheet some attention. For example, the Resources tab of the device's property sheet should list the interrupts, base memory addresses, upper-memory addresses, and (if applicable) Direct Memory Access (DMA) channels that the device is using. You may need to clear the Use Automatic Configuration check box and set one or more of these values manually if you find a conflict reported at the bottom of the Resources tab.
Another place where you can view actual or potential conflicts is the System Information utility. This used to be a snap-in of the Computer Management console, but now you can access it by typing MSINFO32 in the Run dialog box (see Figure 8-6), or by choosing Start?Help and Support and clicking the link labeled Use Tools To View Your Computer Information And Diagnose Problems, and then clicking Advanced System Information in the left window pane.
Figure 8-6: The System Information snap-in contains a wealth of detail.
* The Conflicts/Sharing subfolder lists any conflicting resource assignments (however, see the next section 'IRQ sharing' before concluding that a shared interrupt is actually a problem).
* The Forced Hardware subfolder lists any resource settings that you have made manually via Device Manager, and that therefore Plug and Play may not reconfigure in the future.
The System Information utility can generate reports in custom or text formats. You can also run it remotely by choosing View?Remote Computer.
Tip If you install a device driver that creates an error that you detect in Device Manager or System Information, Windows XP now lets you 'roll back' to the previously installed driver. Open the device's property sheet, click the Driver tab, and click the Roll Back Driver button. Assuming a previous driver exists, you'll get an 'Are you sure?' dialog box and then Windows will revert to the old driver. If no previous driver exists, Windows tells you so, and offers to start the hardware troubleshooter.
Administrators and Plug and Play
An interesting quirk of Plug and Play is that the procedure for automatically installing a device driver doesn't normally require you to be logged on as an administrator - unless Windows asks you to provide a location for the driver file. If Windows can't find the driver itself, it asks you to find it, but you must have administrative rights on the system to do so. I guess the theory is that you could point to a location containing an untrusted and buggy driver if you didn't have administrative experience. Anyway, you may well see an exam question covering this quirk.