Tài liệu The Visible PC pdf

A+ All-In-One Certification Exam Guide, 3rd Edition by Michael Meyers $59.99; ISBN: 0072126795 A+ All-In-One Certification Exam Guide, 3rd Edition by Michael Meyers $59.99; ISBN: 0072126795 Chaper 1 The Visible PC In this chapter, you will: • See the major components of a PC. • Understand the different connectors in a PC. • Recognize the most common devices inside a PC. • Learn how to set jumpers and switches. Mastering the craft of the PC Technician requires you to learn a lot of details about a zillion things. Even the most basic PC contains hundreds of discrete hardware components, each with its own set of characteristics, shapes, sizes, colors, connections, etc. By the end of this book, you will be able to discuss all of these components in detail. In order to understand the details, you often need to understand the big picture first. "The Visible PC" should enable you to recognize the main components of the CPU and to understand their function. You will also see all the major connectors, plugs, and sockets, and learn to recognize a particular part simply by seeing what type of connector attaches to that part. Even if you are an expert, do not skip this chapter! It introduces a large number of terms that will be used throughout the rest of the book. Many of these terms you will know, but some you will not, so take some time and read it. It is handy, although certainly not required, to have a PC that you can take the lid off and inspect as you progress. So get thee to a screwdriver, grab your PC, take off the lid, and see if you can recognize the various components as you read about them. Warning! If you decide to open a PC while reading this chapter, you must take proper steps to avoid the greatest killer of PCs - Electrostatic Discharge (ESD). ESD simply means the passage of a static electrical charge into your PC. Have you ever rubbed a balloon against your shirt, making it stick to you? That's a classic example of static electricity. When that charge dissipates, we barely notice it happening or don't notice it at all, although on a cool, dry day, I've been shocked by a doorknob so hard that I could see a big blue spark! If you decide to open a PC as you read this chapter, jump ahead to the Power Supplies chapter and read up on ESD and how to prevent it - the life you save may be your PC's! CPU The Central Processing Unit (CPU), also called the microprocessor, performs all of the 2 calculations that take place inside a PC. CPUs come in a variety of shapes and sizes, as shown in Figure 1-1. Figure 1: Typical CPUs Modern CPUs generate a lot of heat and thus require a cooling fan or heatsink in order to run cool. (Figure 1-2) You can usually remove this cooling device, although some CPU manufacturers sell the CPU with a fan permanently attached. Figure 2: Installed CPU under a fan CPUs have a make and model, just like an automobile. When talking about a particular car, for example most people speak in terms of a "Ford Taurus" or a "Toyota Camry." When they talk about CPUs, people say, "Intel Pentium III" or "AMD Athlon." Over the years, there have been only a few major CPU manufacturers, just as few companies manufacture automobiles. The two most common makes of CPUs used in PCs are AMD and Intel, although other makers with names such as Cyrix and IDT have come and gone. While there have been only a few manufacturers of CPUs, those manufacturers have made hundreds of models of CPUs. Some of the more common models made over the years have names (or had - most of these names are obsolete) such as 8088, 286, 386, 486, Pentium, Pentium Pro, K5, K6, 6x86, Pentium II, Celeron, Athlon, and Pentium III. In the early years of CPUs, competing CPU manufacturers would sometime make the exact same model, so you 3 could get an AMD 486 or an Intel 486 (Figure 1-3 ). This is no longer true, although some models function similarly, such as the Intel Pentium and the AMD K6. Figure 3: One AMD 486, one Intel 486 CPUs measure potential performance with a "clock speed," much like an automobile has a (theoretical) top speed listed on the speedometer. Manufacturers determine the clock speed - measured in "Megahertz" (MHz) - at the factory. The first CPU used in PCs had a clock speed in the range of 4.77 MHz. Today's CPUs have clock speeds around 1000 MHz. 1000MHz is equal to 1 gigahertz (GHz), so we often see the latest CPUs mentioned in terms of GHz. When talking about a CPU, people often cite the make, model, and clock speed; as in an "833-MHz Intel Premium III" or a "1.2-GHz AMD Athlon." Manufacturers produce CPUs of the same make and model with many different clock speeds. (Figure 1-4) One particular make and model of CPU may come in five or six different speeds! The main reasons for picking one speed over another are the needs of your system - or the thickness of your wallet! Figure 4: Same CPUs, different speeds Finally, CPUs come in different packages. The most common packages are called PGA (Pin Grid Array) and SEC (Single Edge Cartridge). You cannot recognize a CPU solely by its package. Look at Figure 1-5. This figure shows two examples of the popular Celeron processor. Even 4 though these two CPUs are virtually identical in terms of speed and power, they look quite different from each other. Figure 5: Intel Celeron CPUs RAM Random-Access Memory (RAM) stores programs and data currently being used by the CPU. RAM is measured in units called bytes. Modern PCs have many millions of bytes of RAM, so RAM is measured in units called megabytes. An average PC will usually have anywhere from 32 megabytes to 128 megabytes of RAM, although you may see PCs with far more or less RAM. RAM has been packaged in many different ways over the years. The most current package is called a 168-pin DIMM (dual inline memory module). An older type of RAM package - basically obsolete but added here for completeness - is called SIMM (single inline memory module). See Figure 1-6. Figure 6: SIMM and DIMM RAM packages SIMMs and DIMMs come in several different physical packages. The two most common sizes of SIMMs are 30-pin and 72-pin, so named for the number of metal "contacts" along one edge. (Figure 1-7) It is easy to tell the difference between them, as the 72-pin SIMM is much larger than the 30-pin SIMM. 72-pin SIMMs are more modern and can hold more RAM than 30-pin SIMMs. 72-pin SIMMs can also transfer information to and from the CPU faster than 30-pin SIMMs can. 5 Figure 7: 30- and 72-pin SIMM There are also three different sizes of DIMMs used by PCs: a 168-pin DIMM and two sizes of smaller "SO" DIMMs: a 72-pin and a 144-pin version (Figure 1-8). The SO DIMMs' small size makes them very popular in laptops. Most desktop PCs sold today use only the 168-pin DIMMs, although millions of older PCs sport SIMMs. Figure 8: 168-pin DIM and SO-DIMM Motherboard You can compare a motherboard to the chassis of an automobile. In a car, everything connects to the chassis either directly or indirectly. In a PC, everything connects to the motherboard, either directly or indirectly. A motherboard is a thin, flat piece of circuit board, usually of green or gold color, and often slightly larger than a typical piece of notebook paper (Figure 1-9). Figure 9: Photo of bare motherboard 6 A motherboard contains a number of special sockets that accept various PC components. Motherboards provide sockets for the microprocessor (Figure 1-10); sockets for RAM (Figure 1- 11); sockets to provide power (Figure 1-12); connectors for floppy drives and hard drives (Figure 1-13); and connectors for external devices, such as mice, printers, joysticks, and keyboards (Figure 1-14). Figure 10: Socket for CPU Figure 11: Sockets for RAM Figure 12: Sockets for power plug 7 Figure 13: Floppy and hard drive connectors Figure 14: Various external connectors Every motherboard has a few components soldered directly onto the motherboard (Figure 1-15). Figure 15: Soldered components Motherboards use tiny wires, called "traces," to link the various components of the PC together electrically (Figure 1-16). 8 Figure 16: Traces All motherboards use multi-purpose "expansion slots" that enable you to add optional components. Your PC accepts thousands of different types of optional devices, including scanners, modems, network cards, sound cards, and tape backups. The expansion slots create the connection that enables optional devices to communicate with the PC. We generically call a device that connects to an expansion slot an "expansion card," or simply a "card." There are different types of expansion slots for different types of cards (Figure 1-17). Figure 17: Expansion slots - one slot has a card inserted The PC industry long ago standardized the position of the expansion slots and external components. The motherboard mounts inside the "box" or "case," which is the part of the PC that you actually see (Figure 1-18). Figure 18: Motherboard in box The case needs to have holes that enable devices to access the external connectors. Where the motherboard has a connector for a keyboard, for example, the case must have a hole though which you insert the keyboard plug. See Figure 1-19. 9 Figure 19: Keyboard socket visible through hole in box Equally important, if the expansion slots enable you to add cards to the PC, then the case must also provide slots that enable different devices to connect to their cards (Figure 1-20). Figure 20: Inserted card from back of PC Certain types or "layouts" of motherboards require a case designed for that type. Fortunately, motherboards come in only a few different layouts, which requires only a few different types of cases. We will visit this in more detail in the Motherboard chapter. Power Supply The "power supply," as its name implies, provides the necessary electrical power to make the PC operate. The power supply takes standard (in the U.S.) 110-volt AC power and converts it into 12- volt, 5-volt, and 3.3-volt DC power. The vast majority of power supplies are about the size of a shoebox cut in half, and are usually gray or metallic colored (see Figure 1-21). 10 Figure 21: Typical power supply A number of connectors lead out of the power supply. Every power supply provides special connectors for the motherboard (Figure 1-22), and a number of other "general-use" connectors that provide power to any device that needs electricity (Figure 1-23). Figure 22: Power connectors for motherboard Figure 23: General use power connectors You can see the power supply if you look at the back of your PC. It has a connection for a power plug that in turn runs to an electrical outlet and also has a big fan inside. Every PC uses a fan or two to keep the interior of the PC cool (Figure 1-24). Check out both the Power Supply and Motherboard chapters for information detailing power supplies. Figure 24: Power supply fan [...]... floppy drives The floppy drive connects to the computer via a 34-pin ribbon cable, which in turn connects to the motherboard The connection to the motherboard is known as the "floppy controller." In early PCs, the floppy controller was a special card that inserted into an expansion slot but today's PCs all have the floppy controller built into the motherboard (Figure 1-26) Even though the floppy connection... 14 the single largest component inside the PC With the front of the CD-ROM drive visible in the front of the PC, as well as its boxy shape and metallic appearance, you should easily recognize the CD-ROM drive (Figure 1-35) Figure 35: Typical CD-ROM drive When CD-ROM drives were first developed, they had their own special controllers Sound card makers then began to add those special controllers to their... of the described devices sit inside the PC - you can't see how these devices connect unless you open the PC' s case The rest of the components we need to talk about have some type of visible connection on the outside of the system case So before we dive into the realm of sound cards, modems, network cards, mice, etc., you need to understand the many types of connectors (often called "ports") used by these... While the keyboard itself may come in a variety of shapes and sizes, there are basically only two types of keyboard connectors All PCs have a keyboard port connected directly to the motherboard The oldest, but still quite common type is a special DIN-type connector popularly known as the "AT-style." The original IBM PC used the AT-style DIN, and most PCs until recently retained this style connector The. .. hard to believe, but there was a time, long ago and far away, when PCs worked just fine without mice When IBM created the PC, mice were not part of the picture But IBM did something very smart that enabled mice, as well as a lot of other devices invented after the introduction of the PC, to become part of the PC quite easily IBM made the PC easily customizable by providing two ways to add components -... EIDE cable? a The floppy drive cable is round, whereas the EIDE cable is flat b The floppy drive cable is wider than the EIDE cable c The floppy drive cable has a twist in the wires near the end, whereas the EIDE cable runs straight d There is no difference! 10 Which of the following describes a two-wire jumper with a shunt covering the wires? a Off b Open c Closed d Parked Answers 1 a - The central... pins, the video card uses three rows of pins There's nothing else like it in the back of a PC (Figure 1-52) 21 Figure 52: Typical video card Network Cards Networks are groups of connected PCs that share information The PCs most commonly connect via some type of cabling, usually an advanced type of phone cable or coax Network Interface cards (NICs) provide the interface between the network and the PC A... PCs, it told everyone how to write software that could talk to the serial port and manipulate the incoming or outgoing data To top it all off, IBM standardized the serial connector, defining the size, shape, and number and function of all the pins That way you knew if you invented a device that worked in one IBM PC, it would also work in all the others The super-standard IBM serial connector is either... mice For many years, there was no such thing as a dedicated mouse port Mice simply connected via serial ports, either 9-pin or 25-pin The acceptance of the mouse as an integral part of the PC, however, created a demand for the mouse to have its own connector, just as the keyboard had its own connector In the mid-1980s, a new type of mouse connection debuted with the introduction of the IBM PS/2 personal... With the latter, the documentation often describes settings such as "1-2" or "2-3," meaning you should place a jumper on the first and second (1-2) or second and third (2-3) pins But which two of the three are the second and third pins? If you look closely at the board upon which the jumpers are mounted, you should see a small number 1 on one side or the other, identifying the first pin You would then . quite large, usually 15 the single largest component inside the PC. With the front of the CD-ROM drive visible in the front of the PC, as well as its boxy. in turn connects to the motherboard. The connection to the motherboard is known as the "floppy controller." In early PCs, the floppy controller