create 2d barcode c# Safely Remove Hardware Application in C#.NET

Creating Quick Response Code in C#.NET Safely Remove Hardware Application

Before you remove a device from a bus that supports hot plugging, check to see whether the Safely Remove Hardware icon appears in the notification area. If it does, it is recommended that you use the Safely Remove Hardware application to notify the operating system that the device is about to be unplugged.

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To notify the operating system about removing a Plug and Play device 1. Click the Safely Remove Hardware icon in the notification area. The icon displays a notification bubble with a list of devices currently attached to the system. 2. Click the device you want to remove. The device is stopped and can then be unplugged.

Windows XP Professional includes many features that help ensure that the device drivers installed on your computer are reliable and up to date. Drivers are signed by Microsoft after they pass a series of tests for reliability. Windows XP Professional checks for a digital signature whenever a driver is installed and issues a message if the driver is not signed. In addition, drivers that are known to cause problems in Windows are blocked from loading or installing, because Windows XP Professional checks a database of known problem drivers when the computer is started or when a device driver is loaded. If the driver is located in the database of known problem drivers, it cannot be installed or used on your computer. Another feature is Windows Update, a Web site where updated versions of signed drivers are available for download. These and other Windows XP Professional features for device drivers contribute to a stable computing environment and are discussed here in more detail. Device Manager provides details about device drivers on the device s Properties page. Click the Driver tab and select Driver Details to list all the drivers the device is using. Driver details displayed include whether the driver is signed, its version, and whether it has been blocked from loading. For more information about Device Manager, see Device Manager earlier in this chapter.

Microsoft uses a multistage process to test device drivers. Drivers are subjected to compatibility tests administered by the Windows Hardware Quality Lab (WHQL), and drivers that successfully complete the process are digitally signed. Because of this testing, signed drivers are typically more robust and reliable. Once a driver is digitally signed, Windows XP Professional recognizes it when it is loaded. Windows XP Professional notifies the user if a driver is not signed or if a driver file has been changed since its inclusion in the Windows Catalog, which contains an up-to-date list of hardware that is supported for Windows XP by Microsoft. Tip

The Windows Catalog at http://www.microsoft.com/windows/catalog replaces the older Hardware Compatibility List (HCL), but you can still access text-only versions of the HCL for different Windows versions from Windows Hardware and Driver Central at http:// winqual.microsoft.com/download.

The digital signature is associated with individual driver versions, and it certifies to users that the driver provided with the device is identical to the driver that was tested.

Part II:

The following three driver-signing policy settings in the operating system enforce signature verification and determine what the operating system does with an unsigned driver:

Warn Checks the signature on the driver before installation, and displays a warning if the signature verification fails. The driver can still be installed, although installation is not recommended. Block Checks the signature on the driver before installation, and blocks installation of the driver if the signature verification fails. Ignore Silently checks the signature on the driver, logs any unsigned driver files to a log file, and allows the installation of the driver.

Note The computer displays the Warn dialog box if you try to replace a signed driver with an unsigned driver, even if the policy is set to Ignore.

Warn is the default setting. You can change the driver-signing policy for a user without administrator permissions, but you must have administrator permissions to change the driver-signing policy setting for a computer. Group Policy settings can be used to change the driver-signing policy from the defaults. For more information about using Group Policy, see 5, Managing Desktops. To set signature verification options 1. In Control Panel, open Performance and Maintenance, and then open System. 2. Click the Hardware tab, and then click Driver Signing. 3. Under What action do you want Windows to take , click the option for the level of signature verification that you want to set. For more information about file signature verification and signature checking, see Appendix C, Tools for Troubleshooting. Note If you are logged on as a member of the Administrators group, you can apply the selected driver-signing setting as the default for all users who log on to a computer by clicking Make this action the system default.