Using the System Utilities

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11. If present, click the Power Management tab. You can this tab to control how the
network adapter interacts with power management. This tab may not be available if
your Windows 7 installation is virtualized.
12. Click Cancel.
13. Close Computer Management.
Device Driver Signing
Windows 7 uses file signatures on system files to ensure system stability. Device drivers can also
be signed. Device driver signing ensures that a driver for a specific hardware component has been
verified by Microsoft to be from a known software publisher (meaning it is authentic). Device
driver signing also ensures that the device driver has not been modified in any way since it was
signed (meaning it has integrity). Viruses are unable to spread by using device drivers because
digital signing shows an infected device driver as corrupted.
If you attempt to install an unsigned device driver in Windows 7, one of the following messages
will appear:
• Windows can’t verify the publisher of this driver software— This message appears when
no digital signature is present, or the digital signature cannot be verified as valid. You
should install unsigned drivers only if you are confident it is from a legitimate source.
• This driver software has been altered—This message appears if the device driver has been
altered since the developer added the digital signature. In most cases, this message indicates
that the original device driver has been infected by a malicious program and it should not
be installed.
• Windows cannot install this driver software—This message appears only on the 64-bit
versions of Windows 7. The 64-bit versions of Windows 7 do not allow unsigned device
drivers to be installed by default. However, for testing purposes, you can disable the check
for driver signing by using bcdedit.exe.
You can verify that existing drivers and system files are signed by running the File Signature
Verification utility (sigverif.exe). The filename, location, modification date, and version number
are returned for each unsigned file. You can then investigate whether signed versions of these
files are available. It is a best practice to use only signed device drivers.
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A signed device driver does not indicate that Microsoft has performed
stability or quality testing. Only devices in Windows 7 Compatibility Center
have undergone testing by Microsoft.
Hardware Component Installation
When hardware components are installed in a computer, they are assigned resource settings that
allow them to access the system processor and memory in different ways. Each type of hardware
component has different requirements.
The four main resources a hardware component might use are:
• Direct memory access (DMA) channels—A legacy method for allowing devices to communicate
directly with system memory instead of passing data through the processor. Typically
used for sound cards.
• Input/output (I/O) ranges—Addresses at which a device can be communicated with. A
single device can have several addresses, with each address allowing access to a particular
device feature or component.
• Interrupt request (IRQ) lines—A mechanism for devices to request time from the CPU.
• Memory address ranges—Address ranges in system memory that are dedicated to the
device.
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