CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [109]
Device drivers come with the device when you buy it. When you buy a sound card, for example, it comes with a CD-ROM that holds all of the necessary device drivers (and usually a bunch of extra goodies). The generic name for this type of CD-ROM is installation disc. In most cases, you install a new device, start the computer, and wait for Windows to prompt you for the installation disc (Figure 7-27).
Figure 7-27 Windows asking for the installation disc
You might want to add or remove device drivers manually at times. Windows uses a special database called the Registry that stores everything you want to know about your system, including the device drivers. You shouldn’t access the Registry directly to access these drivers, but instead use the venerable Device Manager utility (Figure 7-28).
Figure 7-28 Typical Device Manager
By using the Device Manager, you can manually change or remove the drivers for any particular device. You access the Device Manager by first opening the System applet in the Control Panel; then select the Hardware tab and click the Device Manager button. Make sure you know how to access the Device Manager. You’ll see lots more of the Device Manager as you learn about different types of devices in the rest of the book.
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NOTE You can also access the Device Manager by right-clicking My Computer or Computer and selecting Manage. When the Computer Management dialog box comes up, click on Device Manager.
BIOS, BIOS, Everywhere!
As you should now understand, every piece of hardware on a system must have an accompanying program that provides the CPU with the code necessary to communicate with that particular device. This code may reside on the system ROM on the motherboard, on ROM on a card, or in a device driver file on the hard drive loaded into RAM at boot. BIOS is everywhere on your system, and you need to deal with it occasionally.
Practical Application
Power-On Self Test (POST)
BIOS isn’t the only program on your system ROM. When the computer is turned on or reset, it initiates a special program, also stored on the system ROM chip, called the power-on self test (POST). The POST program checks out the system every time the computer boots. To perform this check, the POST sends out a command that says to all of the devices, “Check yourselves out!” All of the standard devices in the computer then run their own internal diagnostic—the POST doesn’t specify what they must check. The quality of the diagnostic is up to the people who made that particular device.
Let’s consider the POST for a moment. Suppose some device—let’s say it’s the keyboard controller chip—runs its diagnostic and determines that it is not working properly. What can the POST do about it? Only one thing really: tell the human in front of the PC! So how does the computer tell the human? PCs convey POST information to you in two ways: beep codes and text messages.
Before and During the Video Test: The Beep Codes
The computer tests the most basic parts of the computer first, up to and including the video card. In early PCs, you’d hear a series of beeps—called beep codes—if anything went wrong. By using beep codes before and during the video test, the computer could communicate with you. (If a POST error occurs before the video is available, obviously the error must manifest itself as beeps, because nothing can display on the screen.) The meaning of the beep code you’d hear varied among different BIOS manufacturers. You could find the beep codes for a specific motherboard in its motherboard manual.
Most modern PCs have only a single beep code, which is for bad or missing video—one long beep followed by two or three short beeps.
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CAUTION You’ll find lots of online documentation