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Chapter 1: System ModulesThis chapter introduces you to basic computer concepts, including how to identify and replace common components. Familiarity with the components, as well as a good working knowledge of their function, will allow you to work comfortably with most types of computers, in spite of different layouts or new component designs.
You will also be introduced to installation procedures for some common devices. The installations discussed in this chapter are limited to those components that require only physical attachment to the computer to function properly. More complex installations are discussed in Chapter 2.
This chapter also discusses the system resources that allow components to operate within the computer without conflicting with one another. Finally, this chapter describes the physical cables and connections used by devices to communicate with one another, as well as various methods of communication.
This section describes common devices called field-replaceable modules as well as their role in the computer system as a whole. This information will form the foundation of your ability to discover and resolve computer problems. If you know the functions of each component, you will more easily be able to determine which component is at fault when something goes wrong.
Each internal and external component is connected to the system board. The system board, also referred to as the main board, the motherboard, or the planar board, is made of fiberglass and is typically brown or green, with a meshwork of copper lines (see Figure 1-1). These "lines" are the electronic circuits through which signalstravel from one component to another and are collectively called the bus.
The Processor or CPU
Most computer components are designed to perform only one or a limited number of functions, and they only do so when it is specifically requested of them. The device responsible for organizing the actions of these components is the processor, also referred to as the central processing unit, or CPU. As the "brain" of the computer, the processor receives requests from you, the user; determines the tasks needed to fulfill the request; and translates the tasks into signals that the required component(s) can understand. The processor also does math and logic calculations. For more information about this feature, see Chapter 5, "Motherboard, Processors, and Memory."
The processor itself comes in several physical forms. Older processors, such as the Intel 80286, 80386, 80486, and Pentium, have pin grid array (PGA) forms. PGA processors, as shown in Figure 1-2, are square, with several rows of pins on the bottom. These pins are used to attach the processor to the motherboard.
A newer processor form (used in Pentium II and up) is the single-edge contact (SEC) cartridge, which has an upright design and attaches to the motherboard using a slot-1 connector. An SEC processor is shown in Figure 1-3. Processor designs, models, and speeds are discussed in more detail later in the chapter and again in Chapter 5.
The Power Supply
The power supply (shown in Figure 1-4), typically located at the back of the computer's interior, has several very important functions. It is responsible for converting the alternating current (AC) voltage from wall outlets into the direct current (DC) voltage that the computer requires. The power supply accomplishes this task through a series of switching transistors, which gives rise to the term switching mode power supply.
Another function of the power supply is to ensure that the computer receives the proper amount of voltage. Typical North American wall outlets generate about 110-120 vAC (volts AC). However, computers require comparatively smaller voltages±12, ±5, or ±3.3 vDC (volts DC). The computer's power supply removes the excess voltage and dissipates it in the form of heat.
This build-up of heat can cause computer components (including the power supply itself) to fail. Therefore, the power supply has a built-in fan that draws air in from outside the computer case and cools off the components inside...