Managing Device Drivers
Device drivers are programs that control a device. They each act like a translator between the device and programs that use the device. Each device has its own set of specialized commands that only its drivers knows. Whereas most programs access devices by using generic commands, the driver accepts the generic commands from the program and translates them into specialized commands for the device.
Device drivers are needed for a device to work. These drivers can be retrieved from the following sources:
- Bundled with Windows Vista
- Supplied with a device
- Updated with Windows Update
- Updated from the manufacturer's website
Sometimes you might have to download an updated driver from Microsoft or the manufacturer's website to fix problems with device functionality caused by poorly written drivers or by changing technology.
Plug-and-play refers to the capability of a computer system to automatically configure expansion boards and other devices. You should be able to plug in a device and play with it, without worrying about setting DIP switches, jumpers, and other configuration elements. If you connect USB, IEEE 1394, and SCSI devices to a Windows Vista system, Windows Vista will automatically detect these devices. When you connect a PCI or AGP plug-and-play expansion card and turn on the computer, Windows Vista will detect these devices. If Windows Vista does not have a driver available on the device after detection, Windows Vista will prompt you to provide a media or path to the driver.
To ensure reliable drivers, Microsoft implemented signed drivers starting with Windows 2000. A signed driver is a device driver that includes a digital signature, which is an electronic security mark that can indicate the publisher of the software and information that can show whether a driver has been altered. When it is signed by Microsoft, the driver has been thoroughly tested to make sure that the driver will not cause problems with the system's reliability and not cause a security problem.
By default, if a driver is not signed, signed by a publisher that could not be properly identified, or has been altered since its release, Windows Vista will notify you. Of course, you should install only drivers that are properly signed.
Device drivers that are included on the Windows Vista installation DVD or downloaded from the Microsoft update website include a Microsoft digital signature (making it a signed driver). If you have problems installing a driver or device is not working properly, check with Microsoft's update website and visit the device manufacturer's support website to obtain an up-to-date digitally signed driver for your device.
The Device Manager lists all hardware devices on your computer and allows you to change the properties for any device. Using the Device Manager, you can view a list of installed devices (see Figure 3.8). When a device is added to the system, the device list is re-created.
Figure 3.8 Windows Vista Device Manager. The exclamation point indicates a problem with the Mass Storage Controller driver, and the down arrow indicates the Conexant AC-97 audio device is disabled.
To access the Device Manager, you must be logged on to the system as an administrator. To Open Device Manager, click the Start button, click Control Panel, click System and Maintenance, and then click Device Manager. If you are prompted for an administrator password or confirmation, enter the password or provide confirmation.
If you locate and double-click a device, you will be able to do the following (see Figure 3.9):
- Uninstall a device. The Device Manager can be used to uninstall the device driver and remove the driver software from the computer.
- Enable or disable devices. Instead of uninstalling the driver installer, you can use the Device Manager to disable the device. The hardware configuration is not changed.
- Update device drivers. If you have an updated driver for a device, you can use the Device Manager to apply the updated driver.
- Roll back drivers. If you experience system problems after you update a driver, you can roll back to the previous driver by using Driver Rollback. This feature enables you to reinstall the last device driver that was functioning before the installation of the current device driver. If there's no previous version of the driver installed for the selected device, the Roll Back Driver button will be unavailable.
- Troubleshoot devices. If a device is not operating correctly, you can use the Device Manager as part of your troubleshooting process. For example, you might see a device listed as Unknown Device next to a yellow question mark.
Figure 3.9 If you double-click a device in Device Manager, you can then update the driver, roll back the driver, disable the device, or uninstall the driver.