A+ Hardware Core Service Technician Maintenance Manual CORE HARDWARE SERVICE TECHNICIAN 2 CHAPTER 1 Ports and Connectors 2 Introduction 2 Objective 1.01 Common Peripheral Ports 2 Assigning System Resources: I/O Addresses and IRQs 2 Serial Ports 2 Parallel Ports 2 Objective 1.02 Standard Connectors and Cabling 2 The Keyboard 2 The Mouse 2 Video 2 Audio 2 MIDI/Joystick Ports 2 Modems 2 Network Cards 2 Printers 2 Objective 1.03 Enhanced Ports and Connectors 2 USB 2 IEEE-1394 2 SCSI 2 SUMMARY 2 Chapter 2 Maintenance and Safety Precautions 2 Objective 2.01 Preventative Maintenance Procedures 2 Liquid Cleaning Compounds 2 Clean or Soapy Water and a Damp Cloth 2 Denatured Alcohol 2 Glass Cleaner 2 Fabric Softener 2 Cleaning Contacts and Connectors 2 Denatured Alcohol 2 Erasers 2 Non-Static Vacuums 2 Compressed Air 2 Lint-Free Cloths 2 Objective 2.02 Component Protection and Storage 2 Brownouts 2 Blackouts 2 Power Spikes 2 Lightning Storms 2 EMI 2 Saving Your PC from Electrical Problems 2 Uninterruptible Power Supplies 2 Standby Power Systems 2 Online UPSs 2 Surge Suppressors 2 Storing Components for Future Use 2 Objective 2.03 Potential Hazards and Proper Safety Procedures 2 High-Voltage Equipment 2 Power Supplies 2 Monitors 2 Fires 2 Objective 2.04 Disposal Procedures and Environmental Guidelines 2 Batteries 2 CRTs 2 Toner Kits and Cartridges 2 Chemical Solvents and Cans 2 Material Safety Data Sheet 2 Objective 2.05 Electrostatic Discharge Precautions and Procedures 2 How ESD Is Apparent or Hidden 2 Hidden ESD 2 Catastrophic ESD 2 Degradation 2 Common ESD Protection Devices 2 Anti-Static Wrist and Ankle Straps 2 Anti-Static Mats 2 Anti-Static Floor Mats 2 Anti-Static Bags 2 Anti-Static Spray 2 Fabric Softener 2 Potential Dangerous or Hazardous Situations 2 SUMMARY 2 Chapter 3 Motherboards, Buses and Power supplies 2 Objective 3.01 Common Motherboards: Components and Architecture 2 Full AT and Baby AT Form Factors 2 ATX 2 SIMMs and DIMMs 2 Processor Sockets 2 External Cache Memory 2 Objective 3.02 Common PC Expansion Buses 2 ISA 2 EISA 2 VESA Local Bus 2 PCI 2 AGP 2 USB 2 Basic Compatibility Guidelines 2 Support for Mass Storage Devices 2 SCSI Support 2 Objective 3.03 AT and ATX Power Supplies 2 Motherboard Power 2 AT Power Connectors 2 ATX Power Connector 2 Connections to Peripherals 2 Molex Connectors 2 Mini Connectors 2 Wattage 2 Sizes 2 SUMMARY 2 CHAPTER 4 CMOS Setup Utility 2 Objective 4.01 BIOS, Hardware, and the Boot Process 2 POST 2 Beep Codes and Error Codes 2 Objective 4.02 CMOS Setup Utility 2 CMOS Settings 2 SUMMARY 2 CHAPTER 5 Processors 2 Objective 5.01 Intel Processors 2 Pentium 60 and 66 MHz 2 Pentium 75-200 MHz 2 Intel Pentium Pro Processors 2 Intel Pentium MMX Processors 2 Intel Pentium II Processors 2 Intel Celeron Processors 2 Intel Pentium III Processors 2 Objective 5.02 AMD Processors 2 AMD K5 Processors 2 AMD K6 Series of Processors 2 AMD Athlon Processors 2 AMD Duron Processors 2 Objective 5.03 Cyrix Processors 2 SUMMARY 2 CHAPTER 6 RAM 2 Objective 6.01 Common Types of RAM 2 SRAM (Static RAM) 2 DRAM (Dynamic Random Access Memory) 2 EDO RAM 2 SDRAM (Synchronous Dynamic RAM) 2 RDRAM 2 VRAM (Video RAM) 2 WRAM (Windows Accelerator Card RAM) 2 Objective 6.02 Installing RAM Modules 2 SIMMs (Single Inline Memory Module) 2 DIMMs (Dual Inline Memory Module) 2 RIMM (Rambus Inline Memory Module) 2 Objective 6.03 Memory Banks 2 Objective 6.04 Error-Checking RAM: Parity and ECC 2 Objective 6.05 RAM and CMOS 2 SUMMARY 2 CHAPTER 7 IDE Devices 2 Objective 7.01 IDE Drives 2 Connections 2 Jumpers 2 Objective 7.02 EIDE Devices 2 Connections and Jumpers 2 The Return of Cable Select 2 Objective 7.03 CMOS AND EIDE 2 Objective 7.04 Preparing Hard Drives to Hold Data 2 Partitioning 2 Formatting 2 SUMMARY 2 CHAPTER 8 SCSI 2 Objective 8.01 Fundamentals of SCSI 2 SCSI IDs 2 Termination 2 Objective 8.02 SCSI Types 2 SCSI-1 2 SE, HVD, and LVD SCSI 2 SCSI-3 2 Objective 8.03 Internal vs. External SCSI Devices 2 Objective 8.04 SCSI Cabling 2 Types of SCSI Cables 2 Types of External Connectors 2 Objective 8.05 Proper Procedures for Installing and Configuring SCSI Devices 2 Objective 8.06 Address / Termination Conflicts 2 SUMMARY 2 CHAPTER 9 Upgrading System Components 2 Objective 9.01Upgrading System Memory 2 Objective 9.02 Adding or Replacing Hard Drives 2 Add or Replace? 2 Adding a New Drive 2 Objective 9.03 Replacing the CPU 2 Objective 9.04 Upgrading the System BIOS 2 Replacing the BIOS 2 SUMMARY 2 CHAPTER 10 System Resources 2 Objective 10.01 I/O Addresses 2 The Rules of I/O Addresses 2 IRQs 2 The Rules of IRQs 2 COM and LPT Ports 2 Physical vs. I/O Ports 2 COM3 and COM4 2 LPT Ports 2 COM and LPT Ports Today 2 Objective 10.03 DMA 2 DMA Limitations 2 Bus Mastering 2 What Uses Classic DMA? 2 Understand the "Big Three!" 2 Objective 10.04 Plug and Play 2 Identifying Plug and Play 2 How Plug and Play Works 2 SUMMARY 2 Chapter 11 Installing and Configuring Peripherals 2 Objective 11.01 Assembling the PC 2 Power Supply and wiring 2 The Motherboard 2 CPU 2 PCI 2 AGP 2 Video Card Installation 2 CMOS Options for Video 2 Keyboard 2 Objective 11.02 Adding the Basic Ingredients 2 Monitors 2 Display Settings 2 Refresh Rate 2 Dot Pitch 2 Interlacing 2 Video System 2 Floppy Drives 2 Inserting Ribbon Cables 2 Hard Drive 2 Mouse 2 CD-Media Drives 2 Objective 11.03 Installing Devices 2 Know the Device You're Installing 2 Install the Device 2 Handling Cards 2 Installing Legacy Devices 2 Inspect and Verify 2 Objective 11.04 Installing Other Common Peripherals 2 Modems 2 Installation 2 Communication Programs 2 Windows 2000 2 NICs 2 Sound Cards 2 Installation 2 Device Manager 2 Control Panel 2 Objective 11.05 Using the Device Manager as a Troubleshooting Tool 2 SUMMARY 2 Chapter 12 Printers 2 Objective 12.01 Printers 2 Dot Matrix Printers 2 Inkjet Printers 2 Laser Printers 2 Laser Printer Parts 2 The Laser Printing Process 2 Other Laser Printer Components 2 Objective 12.02 Printer Connections and Configurations 2 Serial Printers 2 Parallel Printers 2 The Parallel Port 2 The IEEE 1284 Standard 2 Byte Mode/ Enhanced Bi-directional Port 2 Enhanced Parallel Port (EPP) 2 Extended Capabilities Port (ECP) 2 USB Printers 2 Network Printers 2 Network Printers 2 Objective 12.03 Troubleshooting and Preventive Maintenance 2 Feed and Output 2 Problems with Friction Feed Mechanisms 2 Problems with Tractor-Feed Mechanisms 2 Printer Errors 2 Out of Paper Errors 2 Input/Output Errors 2 Incorrect Port Mode Errors 2 No Default Printer Errors 2 Toner Low and Ink Low Errors 2 Paper Jams 2 Print Quality 2 Dot-Matrix Print Quality Issues 2 Inkjet Print Quality Issues 2 Laser Print Quality Issues 2 General Print Quality Issues 2 Preventive Maintenance 2 Cleaning Dot Matrix Printers 2 Cleaning Inkjet Printers 2 Cleaning Laser Printers 2 SUMMARY 2 Chapter 13 Troubleshooting Hardware 2 Objective 13.01 System Components 2 CPUs 2 Installation Issues 2 Heat Issues 2 Motherboards 2 Before and During the Video Test: The Beep Codes 2 After the Video Test: The Error Messages 2 Solution 2 Troubleshooting RAM 2 Objective 13.02 Mass Storage Devices 2 Troubleshooting Hard Drives 2 When Good Drives Go Bad 2 Troubleshooting SCSI Devices 2 Troubleshooting CD Media Drives 2 Cleaning Your CD Media Drive and Discs 2 Troubleshooting Floppy Drives 2 Objective 13.03 Expansion Cards and Peripherals 2 Troubleshooting Monitors 2 External Adjustments 2 Internal Adjustments 2 Troubleshooting Video Cards 2 Troubleshooting Modems 2 Is the Modem Using a Non-Conflicting COM Port and IRQ? 2 The Software Says There's No Modem 2 The Modem Works Sporadically 2 Troubleshooting Sound Cards 2 Physical Problems 2 Drivers 2 Support Resources 2 CODEC Problems 2 SUMMARY 2 Chapter 14 Portable Computers 2 Objective 14.01 Configuration 2 RAM 2 Hard Drives 2 Modular CPUs 2 Video Cards 2 PC Cards 2 CardBus 2 Objective 14.02 Power Management 2 System Management Mode 2 Requirements for APM/ACPI 2 APM/ACPI Levels 2 Configuration of APM/ACPI 2 Objective 14.03 Batteries 2 Nickel-Cadmium (Ni-Cd) 2 Nickel Metal Hydride (Ni-MH) 2 Lithium Ion (Li-lon) 2 Smart Batteries 2 Objective 14.04 USB and FireWire 2 USB 2 USB Configuration 2 FireWire 2 Objective 14.05 Duplex Explained 2 Duplex Capability 2 Duplex and NICs 2 Objective 14.06 Docking Stations 2 Hardware Profiles 2 SUMMARY 2 Chapter 15 Networks: Hardware 2 Objective 15.01 Networking Basics 2 Objective 15.02 Networking Hardware for the PC 2 Installing NICs 2 Software Protocols and Packets 2 Hardware and Packets 2 Infrared 2 Objective 15.03 Network Topologies 2 Bus Topology 2 Reflection and Termination 2 Ring Topology 2 Star Ring 2 Star Bus 2 Objective 15.04 Hardware Protocols 2 Ethernet 2 Thick Ethernet-10Base5 2 Thin Ethernet-lOBase2 2 10BaseT 2 CAT Levels 2 Fast Ethernet 2 Fiber-Optic Ethernet 2 Combining and Extending Ethernet 2 Token Ring 2 STP Types 2 Token Ring Connectors 2 SUMMARY 2 CORE HARDWARE SERVICE TECHNICIAN CHAPTER 1 Ports and Connectors Introduction Mastering the craft of the PC technician requires you to learn a lot of details about what sometimes seems to be about many individual parts, connections, and settings. Even the most basic PC contains hundreds of discrete hardware com¬ponents, each with its own set of characteristics, shapes, sizes, colors, connections, and so on. But don't panic! It's actually much simpler than it seems! Most of these components fit into certain classes or groups-hard drives, for example, all use basically the same cables and connections. Additionally, the PC industry only uses a few different types of connections for a large number of different devices, so once you learn one type of connector you'll know how to use it all over the PC! This chapter covers all the major connectors, plugs, and sockets (and spells out the amazing collection of acronyms and abbreviations used by techs). That's a good bit of knowledge to learn as the A+ exams expect you to recognize a par¬ticular part simply by seeing what type of connector attaches to that part. It is handy, although certainly not required, to have a PC close by so you can take off the lid and inspect its insides as you progress. So get a screwdriver, grab your PC, take off the lid. and see if you can recognize the various components as you read about them. Hint! If you decide to open a PC while reading this chapter, you must lake 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 the balloon stick to you? That's a classic example of static electricity. When that charge dissipates, you may not notice it happening - although on a cool, dry day, I've been shocked so badly by touching a doorknob that I could see a big, blue spark! If you decide to open a PC as you read this chapter, jump ahead to Chapter 2 to read up on ESD and how to prevent it-the life you save may be your PC's! Objective 1.01 Common Peripheral Ports Most techs don't go around saying things like, "just plug that there thing into the thingy on the back of the PC” and you shouldn't either! Every cable used with PCs has a connector at the end that ultimately plugs into a corresponding port on the PC. Connectors and ports can be either male or female, defined as having pins or holes, respectively. Assigning System Resources: I/O Addresses and IRQs Everything in your PC gets assigned a series of I/O (input/output) addresses that enable the CPU to give specific, directed commands. Most devices also get an IRQ (for interrupt request, which controls service requests) that enables them to con¬tact the CPU. This should come as no surprise to you if you've worked with PCs for any length of time. What many new techs do not realize, however, is that all of the standard ports on a motherboard are assigned a set of standard resources, and you can usually change those resources if you run into a conflict with another com¬ponent. Further, most CMOS (Complementary Metal-Oxide Semiconductor) setup utilities enable you to disable the serial and parallel ports to free up resources for the newer style ports, such as USB (universal serial bus) ports. Chapter 4 goes into CMOS settings in more detail, and Chapter 10 discusses system resources in depth. Serial Ports Serial ports transfer data 1 bit at a time and are used to connect mice, external moderns, and other serial devices to the computer. Serial ports can be either 9-pin or 25-pin male ports, as shown in Figure 1-1. All computers have at least one 9 pin serial port, and many still have a 25-pin serial port. Older 25-pin ports used only 9-pins at any given time, so manufacturers quickly came up with the less¬ expensive 9-pin serial ports. Most motherboards have at least one serial port - Serial Port 1 - that gets I/O address 3F8 and IRQ4 (COM1 ) by default, but most enable you to assign any COM address / IRQ to the serial port. If this doesn't make sense check out chapter 10 for details on I/O addresses and IRQs. FIGURE 1-1 25 Pin Serial Port and 9 Pin serial Port Serial ports can communicate with the PC either synchronously or asynchronously. Synchronous communications send data continuously using dummy bits to keep the data flowing, and asynchronous communications send data intermittently with start and stop bits. Parallel Ports Parallel ports are the 25-pin female DB (data bus) ports on the back of your PC, as shown in Figure 1-2. Note the D shape of the port, which should help you remember the official term. Parallel ports traditionally get I/O address 278 and IRQ7 (LPT1 ), but many modern motherboards give you the option to change these settings. Parallel communications transfers data 8 bits, or 1 byte, at a time. Exam Tip Make sure you know that serial ports transfer data at a rate of 1 bit at a time, and parallel ports transfer data at a rate of 8 bits, or 1 byte, at a time. People, often incorrectly refer to parallel ports as printer ports, but many devices other than printers - such as some CD-ROM drives, Zip drives, and scanners - can use parallel ports. Technological advances, such as the ECP (Extended Capabilities Port) and EPP (Enhanced Parallel Port), have kept the parallel port from going into obsolescence. See Chapter 11 for more details. Objective 1.02 Standard Connectors and Cabling In addition to the multipurpose serial and parallel ports, many single - or double - function ports appear on the standard PC. These enable you to connect peripherals such as keyboards, monitors, and the like. FIGURE 1-2 A 25-pin parallel port The Keyboard All keyboards enable you to do one thing - give commands to the PC - but they come in an amazing array of styles, configurations, and connections. Keyboards range from simple, flat, 102 - key typewriter type to curved, ergonomically correct types with 20 extra keys just for daily essentials (such as surfing the Net, playing music, and staring up the calculator). Keyboards connect to the PC with one of three connectors: a round five - pin DIN (for Deutsch lndustrie Norm, often called an AT-style connector), an round six-pin mini-DIN (also commonly called a PS/2 connector), or a universal serial bus (USB) connector. Figure 1-3 shows the DIN and mini - DIN connectors. Keyboard connectors are always male and keyboard ports are always female regardless of the pin type. Many newer PCs can handle several types of keyboard connections through the use of simple adapters. You can plug the keyboard in Figure 1-9, for example, into either a PS/2 port or a USB slot. Even better, the keyboard can act as a USB hub. the USB technology is discussed later in this chapter in Objective 1.03, The Mouse The mouse also enables you to communicate with your PC And, like the key -board mice come in an array of sizes, shapes, and connectors. Mice connect to the computer with 9-pin or 25-pin serial connectors, called DBs or with a mini-DIN (PS/2) connector (see Figure 1-5). Standard serial mice have female connectors that you plug into the male ser¬ial port on the back of your PC. Mini-DIN and PS/2 mice have male connectors that you plug into the female mini-DIN port on the back of your PC. USB mice plug into a female USB slot, often located on the back of the PC but sometimes turning up in odd places (such as on the keyboard shown in Figure 1-4). FIGURE 1-3 A five - pin DIN (top) and six-pin mini-DIN connector FIGURE 1-4 A keyboard that doubles as a USB hub FIGURE 1-5 A serial mouse connector (left) and a PS/2 mouse connector Video Monitors connect to your PC using a DB video connector. Older CGA (Color/Graphics Adapter) and EGA (Enhanced Graphics Adapter) standard mon¬itors used 9-pin female DB connectors. Most of the monitors you see today are VGA (Video Graphics Adapter), SVGA (Super VGA), or XGA (Extended Graphics Array), and connect to the computer using male DB connectors with 15-pins in three rows, as shown in Figure 1-6. Exam Tip VGA, SVGA, and XGA monitors all have the DB connector with 15¬pins in three rows. FIGURE 1-6 A female DB 15-pin connector Audio All sound cards have integrated mini-audio ports. Devices such as microphones and speakers connect to the audio ports using mini-audio connectors. MIDI/Joystick Ports Many sound cards have a female DB-15 port that supports a joystick or MIDI (Musical Instrument Digital Interface) box for attaching musical instruments to the PC. These devices connect to the port using a male DB connector with 15 - pins in two rows. Exam Tip Make sure you know that the DB connector with 15-pins in two rows can be used for both MIDI devices and joysticks. Modems Modems connect to your telephone line using RJ-11 connectors. RJ-11 connec¬tors use two wires and are identical to telephone connectors (see Figure 1-7). The locking clips on the RJ-11 connectors help secure the cable into the jack, or port. RJ-11 ports look identical to phone jacks and are found on your modem. All modems have at least one RJ-11 port, and many modems have two RJ-11 ports -one for the modem and the other for a telephone, so you can use the telephone line for voice when the modem is not in use. FIGURE 1-7 RJ-11 connectors on a modem Network Cards Network Interface Cards (NICs) enable you to plug network cables into the PC and thus experience one of the fundamentally important sides of computing, the joy of network gaming! Most network cables have either an RJ-45 or BNC con¬nector that connects to the NIC in a corresponding port. Some NICs also have the older-style AUI (Attachment Unit Interface) ports. RJ-45 connectors are twisted¬ pair cables that transfer data using four or eight wires. These connectors look like XXL-sized RJ-11 (telephone) connectors and plug in just like a telephone cable. BNC connectors look like cable television connectors. The pin in the center of the BNC connector fits into the hole in the BNC port. After you have connected the BNC connector to its port, you lock it into place by twisting it slightly. The 15 ¬pin AUI ports look exactly like a MIDI or joystick port. Figure 1-8 shows a NIC with both a BNC port (left) and an RJ-45 port. Exam Tip Make sure you know the difference between RJ-11 connectors and RJ-45 connectors, and that you can easily differentiate between the two at a glance. Printers Printers can use either a Centronics port (shown in Figure 1-9), a USB port, or both. Centronics ports are female ports that look like a slot with two metal clips to lock the connector into place. The male Centronics connector looks like a tab covered with contacts. Technicians often refer to these 36 contacts as pins. After connecting the Centronics connector to the printer, you also need to attach the 25-pin male connector at the other end of the cable to the 25-pin female parallel port on the back of your PC. Techs and users in the know always go with IEEE¬1284-compliant parallel cables for attaching parallel devices. Cheap cables can cause problems. See Chapter 12 for the full details on printers. Exam Tip Use IEEE-1284-compliant cables for laser and ink jet printers. You can connect USB printers to the PC using a USB cable. The square con¬nector on the USB cable connects to the printer, and the rectangular connector on the USB cable connects to a USB port on the back of your PC, or to a USB hub. USB is discussed in more detail in the following objective. FIGURE 1-8 A NIC with both a BNC port and an RJ-45 port FIGURE 1-9 A Centronics port Objective 1.03 Enhanced Ports and Connectors Current systems rely heavily on three types of ports for attaching peripherals ¬USB, FireWire, and SCSI (Small Computer System Interface). Each technol¬ogy offers dramatic enhancements in plug and play, ease of use, and speed. USB USB ports transfer data at speeds up to 12 megabits per second, making them much faster than traditional parallel or serial communications. All Windows operating sys¬tems from Windows 95 OEM Service Release 2 (OSR 2) and later support the use of USB. Windows NT does not support USB, but Windows 2000 handles it very well. Exam Tip USB is supported by all Windows Operating Systems after Windows 95 OSR 2 but was not supported by the original release of Windows 95 or Windows NT. USB cables have two connectors. The rectangular Type A connector connects to a USB port or hub. The square shaped Type B connector connects to the USB device. USB devices are hot swappable, which means that you can connect or discon¬nect them at any time without powering down your PC. USB technology enables you to daisy chain up to 127 devices together using only one IRQ. However, for real-life, on-the-job situations it's a bad idea to hit this maximum. Some applica¬tions reserve bandwidth, and you could wind up with quite a mess. Too much of a good thing isn't good! Exam Tip Remember that you can hot swap USB devices, and can daisy chain up to 127 USB devices together using only one IRQ. Many current devices connect via USB, such as keyboards, mice, joysticks, microphones, scanners, printers, modems, and cameras. Some devices, such as keyboards, even act as USB hubs with extra USB ports enabling you to connect other USB devices directly to them (that is, daisy chain them). Hint! For more information about USB, visit http://www.usb.org. IEEE-1394 IEEE-1394 (more glamorously known as FireWire; the terms can be used inter¬changeably) is an exciting communications technology created in a joint effort by Apple, Texas Instruments, and the IEEE (Institute of Electrical and Electronics Engineers). FireWire enables data transfers at speeds up to a very fast 400 megabits per second. Such incredible speeds make this technology perfect for digital video recorders, external hard drives, and other real-time devices. You can add and remove FireWire devices from the PC on the fly, without powering it down. FireWire technology enables you to daisy chain up to 63 FireWire devices together off a single controller, thus using only one set of IRQs, l/O addresses, and direct memory access (DMA) channels. Moreover, you can interconnect up to 1023 FireWire busses, which in theory means that you could connect 64,449 FireWire devices to a single PC. FireWire connectors look like slightly smaller USB connectors, but have one rounded side so that you cannot connect them backward, as shown in Figure 1-10. Hint! For more information regarding FireWire and the IEEE-1394 standard, visit http://www.ieee.org. SCSI Many PCs-especially those on the higher end (read, more expensive) -have a SCSI (pronounced "skuzzy") connector of one sort or another for attaching SCSI devices. SCSI devices have a variety of interfaces, but the 50-pin SCSI-2 port shown in Figure 1-11 is the most common. The 50-pin connector has fine (read, easily breakable) pins that fit only one way into the port. You might also see 68-pin or 25-pin ports on some devices or PCs. To do the amazing variety of SCSI devices and standards jus¬tice, they get their own chapter in Chapter 8. Hint! For more information on SCSI, check out the SCSI Trade Organization at http://www.scsita.org. FIGURE 1-10 FireWire, or IEEE-1394, connector FIGURE 1-11 SCSI-2 port SUMMARY  Objective 1.01: Common Peripheral Ports The 9-pin and 25-pin serial ports and the 25-pin parallel ports are used for connecting serial and parallel devices, respectively, to the PC Serial devices such as mice and modems transfer data 1 bit a time, whereas parallel devices such as printers, scanners, and Zip drives transfer data 8 bits at a time.  Objective 1.02: Standard Connectors and Cabling Keyboards connect to the motherboard with 5-pin DIN (AT-style), 6-pin mini-DIN (P512), or USB connectors. Mice connect to the 9-pin serial bus in older systems; PS/2 or USB in newer systems. Make sure you remember the 15-pin, three-row DB port is for video; whereas the 15-pin, two-row port is for MIDI devices or joysticks (if on a sound card) or for the ancient AUI network connector. Finally, know the difference between the RJ-11 connectors for modems and the RJ-45 connectors for NICs.  Objective 1.03: Enhanced Ports and Connectors USB enables you to hot swap devices and daisy chain up to 127 devices in one PC running Windows 95 OSR 2 or later. The Type A connector goes into the port; the Type B connector goes into the device. FireWire completely eclipses the USB data transfer rate of 12 Mbps, transferring data at a very fast 400 Mbps! Plus, you can hot swap IEEE 1394 devices and daisy chain up to 63 devices off one controller. Finally, the 50-pin port used by SCSI-2 devices and the 68-pin SCSI devices are the most common ones seen on the many SCSI technologies available today. Chapter 2 Maintenance and Safety Precautions Maintaining a well-functioning PC requires that you do a lot more than running an occasional ScanDisk or deleting temporary Internet files. You need to follow some fairly extensive physical maintenance routines, such as cleaning, managing files, removing dust etc. This chapter goes through the important routines. Further, although the PC might look like a safe white box connected to a nice monitor and a quiet laser printer, it can injure an unwary tech¬ sometimes with deadly effect. This chapter examines the most dangerous areas of the PC and peripherals, teaching you what to avoid and how to avoid damaging you or the PC. Let's get started. Objective 2.01 Preventative Maintenance Procedures To prolong the life of your PC, you simply must inspect and clean it regularly. Cleaning your PC on a regular basis can prevent overheating and ESD. Local Lingo ESD Electrostatic discharge is a quick electrical charge that occurs when two objects with different electrical potentials come into contact with each other. More on this subject in Objective 2.05, later in this During the inspection process, look for damaged or cracked components, improperly seated components, frayed cables, and loose connections. Exam Tip Make sure you know that regular cleaning of the PC will prolong the life of your components, help to prevent ESC, and help to prevent overheating. Liquid Cleaning Compounds Before using any liquid cleaning compound make sure that your computer is turned off. If the PC has power when you use liquid cleaners, you run the risk of damaging or shorting out your components, which is an expensive risk to take. Also make sun that the component you have cleaned with a liquid cleaner is thor¬oughly dry before turning your computer back on! Clean or Soapy Water and a Damp Cloth In some cases, you need only a bit of water and a damp cloth for cleaning chores, such as when cleaning the mouse ball, the outside of the mouse, or the exterior of the monitor or computer case. If water alone cannot do the job thoroughly, you can use mild soapy water on your damp cloth. Make sure that the cloth is damp and not wet and that you do not splash or drip water into your components. If the keys on your keyboard start to stick or you have spilled a cup of coffee into your keyboard, or, for that matter, you just know that there is a lot of dirt under the keys, you can clean the keyboard with distilled water. Some techs will use a light silicone spray lubricant, but I find that water does nearly as good a job. Keep in mind that if you want your keyboard to work again, you need to make sure that it is unplugged before you clean it and that it is thoroughly dry before you plug it in again. As a general rule, wait at least 48 hours before re-attaching the keyboard to your system. Denatured Alcohol The best thing to use for cleaning floppy drive heads is denatured alcohol (metholated spirits). But how do you get it in there? You can't just pour it in! You need to use a lint free swab dipped in the alcohol to clean the floppy drive heads, or you can purchase a floppy drive cleaning kit, which almost always comes complete with denatured alcohol. Don't clean the mechanical mechanism with alcohol because the parts are lubri¬cated and the alcohol will dissolve the lubricant. When cleaning your mouse, you can use a damp cloth to clean the cover and ball, as mentioned earlier, but what about the rollers? Some people pick at the rollers with their fingernails to get all of the dirt off them, but if you want to keep your fingernails clean you can use a cotton swab dipped in denatured alco¬hol to help loosen and remove the dirt. Glass Cleaner You need to turn your monitor off before cleaning to avoid damage to the screen. Many technicians clean the monitor screen with regular glass cleaner. Under most circumstances, however, water and a damp cloth will do the job just fine. Water is the safest cleaning liquid you can use on a monitor. When cleaning the LCD dis¬play screen of a laptop, do not use glass cleaner at all. You will melt the screen! Fabric Softener Some technicians like to use a mixture of 1 part fabric softener to 10 parts water to clean the plastic casing of their computer components. As a cleaning solution it's not as good as mild soap and water, but as an anti-static solution it's excellent! Use it after the cleaning process to help protect your computer from the harmful effects of static electricity. Cleaning Contacts and Connectors To protect your contacts and connectors from becoming dirty, avoid touching them with your hands. Your skin contains natural oils that can leave a residue on contacts and connectors, and that residue needs to be cleaned off. Leaving the con¬tacts untouched will reduce the amount of residue and make them easier for you to clean. Denatured Alcohol You should regularly inspect your contacts and clean them with denatured alco¬hol. Denatured alcohol is the best solution for cleaning the oily residue caused by human oil secretions, and it evaporates, leaving no residue behind. Erasers Some technicians use an eraser to rub residue off contacts, but this leaves a residue of its own and may actually rub the contacts right off. If you absolutely must use erasers, make sure you use the white ones, and immediately clean any rubber residue off of the contacts. Never, ever use pink erasers to clean contacts as these contain acids that have the potential to destroy your contacts. Non-Static Vacuums Common household dust kills PCs. Throw in some dog and cat hair and you might as well call a priest right now. A dust buildup can cause dreaded static and can cause your components to overheat and become useless. When removing dust buildup from your keyboard, inside your computer's case, and from your com¬ponents, use a non-static vacuum (shown in Figure 2-1 ). Many hand-held vacu¬ums are designed specifically for use on PCs. Note that you should definitely not use a common household vacuum cleaner. These create static electricity and can damage your PC! FIGURE 2-1 A non-static vacuum Compressed Air Compressed air works well for getting the dust out of power supply fans, expan¬sion slots, and keyboards, but you need to exercise care in using it for blowing the dust off components and the inside of the case. It is not uncommon to blow the dust off one component right onto another component. You also need to exercise extreme care when using compressed air, because the liquid that compresses the air sits in the bottom of the can and is usually not released unless you turn the can upside down or sideways. This liquid can dam¬age or destroy your components. Lint-Free Cloths Lint-free cloths are excellent for removing dust from your computer. The cloths used for cleaning eyeglasses work the best, because they will not scratch surfaces or leave lint behind. Make sure you never use "dry dusting" lint-free cloths and the like for cleaning any¬thing in or on your computer. Cloths such as the Swiffer Sweeper do won¬ders for dusting those hard-to-reach places in your house, but they use static electricity to collect the dust. As you probably know by now, static electricity is computer enemy number one! Objective 2.02 Component Protection and Storage You need to protect Your computing environment from any kind of power surge, or power sags, as either of these events can cause severe damage to your system. Many things outside the control of normal folks cause sags and surges, such as electrical brownouts and blackouts, spikes on the electrical grid, lightning, and electromagnetic interference. Brownouts Power sags are usually caused by brownouts, where your lights may flicker or grow dimmer. In other words, a power sag occurs when the supply of electricity drops dramatically but does not go out completely. When the power or electricity returns to its original level, your computer cannot handle the quick and drastic change and damage may occur. Blackouts Power surges are caused when the power or electricity goes out completely and comes back on suddenly. In the event of a power surge, any files that you have not saved will most likely become corrupted or lost forever. Power Spikes A power spike is a lot more powerful than a power surge and will almost definitely result in the damage of computer components. The damage caused by a power spike can irreparably affect one or several components. Lightning Storms Any time you use your computer, or even leave it plugged in, during a lightning storm you are asking for damage to occur. No commonly available PC accessory can protect your PC from the damage caused by electrical storms. You need to unplug your PC and peripherals with power cords until the storm ceases. Leave no stones unturned: make sure you unplug even your modem, because lightning can travel through the phone lines and cause damage to computers and their com¬ponents through the modem. Exam Tip Make sure you know that in the event of an electrical storm, the only way to protect your system is to completely unplug it, plus all periph¬erals with external power cords. EMI EMI, or electromagnetic interference, is caused not by storms, but by noise created by high voltage between two cables or excessively long cables. When EMI occurs, your PC may experience sags and surges in the amount of electricity that is pro¬vided to it. The threat of EMI can be combated through the use of cables with a Mylar coating and through a noise filter, which will control the amount of elec¬tricity that reaches your PC and remove the EMI. Noise filters can be purchased as stand-alone products or can be incorporated into an uninterruptible power supply (more on those in the next section). Local Lingo EMI Electromagnetic interference occurs when two signals are close enough to each other to interfere with each other. Saving Your PC from Electrical Problems Any kind of power failure, sag, surge, or spike can cause irreversible damage to your PC and its components. So you simply must protect your PC from these events! Fortunately, many products on the market can help you prevent these events from damaging your PC. These products are called uninterruptible power supplies (UPS) and surge suppressors. Uninterruptible Power Supplies A UPS helps in blackout situations, during which the electricity cuts off completely for a period of time, and brownouts, during which the electrical supply sags well below the level needed to run your PC. Every UPS has batteries that provide backup power, thus enabling you to save your work and shut down your PC properly. A UPS is thus sometimes called a battery backup. Note that a UPS does not provide unlimited Power so you can keep working while the city lights are out. What it does provide you is a short window of a couple of minutes to save and shut down. UPSs come in two main varieties, standby power systems (SPS) and online UPS. Both of these will protect your system in the event of a power outage or sag, but they work differently and provide different levels of protection. Exam Tip Don't plug a laser printer into a UPS. They use way too much electric¬ity and will interfere with the primary function of a UPS-shutting down safely. Standby Power Systems An SPS has a battery that begins generating power as soon as the unit detects a sag in the supply of electricity. It takes a split second for the SPS to come online, how¬ever, and therein lies the main disadvantage to using an SPS. The brief lapse of time could result in your files being damaged before the UPS has kicked in. Online UPSs An online UPS, in contrast to an SPS, provides electricity to the PC all the time, using the electricity from the AC outlet simply to recharge its batteries. If you have an electrical brownout or blackout, your PC does not even flinch, and you'll have plenty of time to save and shut down properly. As an added bonus, most online UPS boxes act as power conditioners that help your PC run better. Electricity com¬ing from the power company does not come in a single stream of electrons at con¬stant pressure, but rather in gentle fluctuations. Because the online UPS runs the PC from its batteries, the UPS can provide a much smoother flow of electricity than the typical wall socket. An online UPS costs more than an SPS, but in the long run its benefits justify the expense. Surge Suppressors Surge suppressors help to absorb power surges so that your computer does not feel their effects. They come as either separate modules or incorporated with a UPS. The best suppressors to purchase are the ones with the lifetime or 10-year guar¬antee. When purchasing a stand-alone surge suppressor, avoid the cheapest ones. They are usually little more than power strips and provide minimal protection against power spikes. Exam Tip It is essential that you know that these suppressors will not prevent power spikes in the event of an electrical storm, and in those instances the best thing you can do to protect your system is to unplug your PC and all peripherals with power cords. Don't forget to unplug the phone line from the modem! Power surges and sags can wreak havoc on an unprotected PC, and not just in the obvious ways. ("Hey, my PC got struck by lightning and it's a smoking ruin. Do you think it still works?" ) Common surges and sags can damage power sup¬plies and components, and they can even cause file corruption. The cost of a good UPS and surge suppressor is nothing compared to the cost in time and money caused by lost components or corrupted files that you may have to endure if you don't use either one. APC (American Power Conversion) make good suppressors and UPS. Storing Components for Future Use When storing your computer components for future use, you still need to protect them from the hazards of ESD, corrosion, and other damage. You should store your computer components in cool, dry places. Heat or warmth can cause pre¬mature aging of your components in much the same way that the sun can cause fading of paper. Moreover, heat can also destroy data that has been stored magnetically and dampness can cause corrosion to your components. It is important that you store your components away from high-voltage devices, and never store batteries of any kind for long periods of time. Old batter¬ies can leak or corrode. The safest place to store your components for future use and to protect them from ESD is in an anti-static bag, and for the ultimate in component safety, store the components in their manufacturers' original boxes and packaging. Exam Tip Make sure you know that the safest place to store components for future use is in their original packaging or in an anti-static bag. Objective 2.03 Potential Hazards and Proper Safety Procedures While power issues can cause damage to your PC, many hazards can injure the technician, such as high-voltage shocks or electrical fires. You need to make yourself aware of these hazards and of ways to prevent them from occurring. High-Voltage Equipment The capacitors in PC power supplies, monitors, and laser printers carry very high voltages that can easily cause severe bodily injuries. Fortunately, in most cases you will not have to worry about identifying high-voltage equipment because it is usu¬ally marked by a bright yellow warning sticker that will leave no question about the voltage levels of the components. Whenever you work with a piece of high-voltage equipment, always make sure the device is unplugged and that you have removed your anti-static wrist strap (for more information, see "Anti-Static Wrist and Ankle Straps," later in this chapter). Power Supplies Whenever you work on your computer, you need to make sure it is unplugged. In the old days, you could leave the PC plugged in and thus ensure excellent electri¬cal grounding, but modern PC motherboards always have a small voltage running when the PC is plugged in. Unplug the PC or you will be likely to damage something. When it comes to power supplies, though, even unplugging them does not make them safe to fix. The safest method of repairing power supplies is not to repair them at all. Better to throw them into the recycling bin and install a brand new Power supply. It is extremely risky even to open the case of a Power supply, because the capacitors can hold a serious charge even when the power supply is unplugged. If you must work on a power supply, make sure you remove your anti-static wrist strap and discharge the capacitors on the power supply. A little static elec¬tricity won't bother a power supply at all, but the metal resistor in the strap can attract voltage (or, more importantly, current (amperage)) and lead to bad things-massive jolts through your body can kill, so be careful! Exam Tip As the electricians will tell you, it's the amperage (the amount of elec¬tricity) that'll get you, not the voltage. Power supplies have relatively low voltages, but high current (amperage). Use caution when working on power supplies. You might have the brilliant idea of rewiring a power supply to make it last just a little bit longer until you can get to a store to purchase a replacement. After carefully twisting all the wires and wrapping them in electrical tape, you plug the power supply back into the PC and into the wall. The result would likely be sparks flying from the wall, blue flames coming out of the power supply plug, and a jolt that knocks you dear across the room. (Not that I've ever done that!) Monitors Never open a monitor unless you know exactly what you are trying to accomplish. The voltages inside can kill you. The capacitors in a typical PC monitor also carry extremely high voltages even when unplugged. In addition to the line voltage and capacitors, the flyback transformer is a dangerous part of the monitor. You don't know what that is? Then that is a good reason to keep out! Most adjustments are accomplished through controls on the front of the monitor. Internal adjustments are rare and require plastic tools and schematic lay¬outs. A technician who hasn't been trained in monitor repair should not open one. Local Lingo CRT Cathode ray tubes are used in monitors and television screens and move a beam of light across the back of the screen to produce the image on the screen. Most techs use the terms CRT and monitor interchangeably. If you must work on a CRT, you have two options. First, you can unplug and discharge the monitor. (Talk to a television repair person for details.) Make your fixes, and then plug in the monitor and turn it on. Repeat as necessary. Or second, you can simply leave the monitor powered up so you can see what you're doing and hopefully fear will keep you from doing anything incorrectly. Both methods leave a lot to be desired, don't you think? Hint! In either case, never wear your anti-static wrist strap when working on a CRT to avoid the possibility of the voltages being trans¬ferred to your body front the CRT. If this happens, you will most likely die. Fires Most of us will never experience a PC fire, but we may experience an electrical fire in our homes. It is important that you realize that just as smoke can harm you, it can also harm your PC and its components. If you do experience a computer fire, or any electrical fire for that matter, never, ever throw water on it, because throwing water on an electrical fire can cause the electrical current to travel up the water and straight into you! Instead, if you expe¬rience an electrical fire, make sure you use a type C or a type ABC fire extinguisher. Exam Tip Make sure that you know that you need to use a type C or type ABC fire extinguisher to put out a fire in a computer. In fire situations, people have a tendency to panic, so you need to know the safety procedure at your workplace ahead of time and know the precise locations of the fire extinguishers in case you ever need to use them. Objective 2.04 Disposal Procedures and Environmental Guidelines Many computer components, such as batteries, CRTs, chemical solvents, and toner kits (for printers), contain harmful ingredients. Don't throw these items in the garbage! Many of these items can be recycled, and a hazardous waste program can remove most. Exam Tip Make sure you know the proper disposal procedures for each of the following items prior to taking the exam. Batteries Batteries for the computer often contain lithium, mercury, or nickel-cadmium, which means that if they were to be thrown in the garbage and carried off to a landfill site, they could contaminate the water and soil. You can take batteries to a recycling depot or, in some cases, send them back to the manufacturer. CRTs Many CRTs contain lead. If you dump them in the trash (and ultimately in a landfill), you may contaminate the soil and water in your area and poison people. Don't do it! For this reason, CRTs must be recycled or turned over to a hazardous waste program. Toner Kits and Cartridges The main concern about the disposal of toner kits and cartridges is that there are to many of them. Most people go through several a year, and if they were all thrown in the garbage, they would fill a landfill site. There are many ways of deal¬ing with toner kits and cartridges. You can now refill these cartridges, which saves on environmental wear but wreaks havoc on your printer. The printing quality from refilled cartridges is often less than that of new cartridges and the refilled ink can cause the bubble jets on ink-jet printers to clog. Many manufacturers of these cartridges will buy back the used cartridges, refill them, and then resell them, which is probably the best solution. Chemical Solvents and Cans Chemical solvents or cans for PC use (or for any other use, for that matter) con¬tain many harmful chemicals that should not be placed in the ground. For this reason, you simply cannot throw these in the garbage or they may damage the soil and water supply. Instead, chemical solvents and cans must be picked up through a hazardous waste program. Material Safety Data Sheet Most compounds, chemicals, and components come with a Material Safety Data Sheet (MSDS) that contains information about the product as well as any warn¬ings, safe disposal requirements, and safe methods of transportation. If an item comes without an MSDS, you can obtain one from the manufacturer or locate one on the Internet. Hint! For more information about MSDSs, or to search for an MSDS, visit http://www.msdssearch.com/. Objective 2.05 Electrostatic Discharge Precautions and Procedures This chapter has mentioned numerous times about the dangers of ESD, but now it's time for some details. Dust and ESD are the two main enemies of your computer. To maintain your computer and to prolong the life of compo¬nents, you need to learn about the effects of ESD and how to protect your com¬puter from those effects. How ESD Is Apparent or Hidden A prime example of ESD, or electrostatic discharge, is the small shock you receive when you walk across a carpeted floor and then touch an object or a person. Zap! The electrical discharge doesn't do you any lasting damage, but such a seemingly harmless shock will destroy computer components. In fact, even discharges well below the level that you can feel will still damage or destroy PC components-and you won't even know! Hint! To learn more about ESD, visit http://www.ce-mag.com/esdhelp.html. Hidden ESD A real concern, and another good reason to clean your computer regularly is that the dust buildup on PC components can cause an electrical charge that you probably will not be aware of at the time. In most cases, you will not even be aware that a problem exists until a component begins to behave erratically, and by that point it will be extremely difficult or impossible to pinpoint the original source of the problem. Catastrophic ESD Catastrophic ESU causes a computer component to fail immediately. When cata¬strophic ESD occurs, it will be obvious, You can remove the component and replace it with a new one, and it most likely will not affect any other components. Degradation Degradation occurs when the effects of ESD are not immediately apparent in their full force, and the effects gradually get worse and worse. Degradation will cause your components to work erratically and can make the original problem hard to recognize. This condition can affect your other system components and cause their failures also. Common ESD Protection Devices Many devices are available that can help to protect your system from the effects of ESD to ensure a longer life for your components. These devices include anti-sta¬tic wrist and ankle straps, anti-static mats, anti-static floor mats, anti-static bags, and anti-static sprays. Exam Tip Make sure you know what ESD is and what devices can protect your system from its effects. You can help prevent the effects of ESD by grounding yourself by touching the exterior of the PC power supply before touching any of your system's compo¬nents. Remember, though, that you are only at the potential of the system as long as you hold on to the chassis. When you let go, you can build up potential and cause an ESD event. Local Lingo Electrical potential Everything has a certain electrical potential, or how charged it is relative to the zero ground of the Earth. Note the term relative. If your body has a +3000-volt charge and you touch a component that also has a +3000 volt charge (working in the International Space Station, perhaps?), no damage will occur. As far as you and the component are concerned, you're at the same electrical potential. Touch a component that has a -3000 volt charge, on the other hand, and watch the sparks fly! Anti-Static Wrist and Ankle Straps Anti-static wrist and ankle straps are composed of a wire with a 1 megaohm resis¬tor. They keep you at the same relative electrical ground level as the computer components on which you're working, as long as you set them up properly. Anti-static devices have a strap that you wrap around your wrist or your ankle on one end. Some anti-static straps have a clip on the other end that you can attach to a metal device to ground yourself (see Figure 2-2), or a prong at the other end that you plug into the ground wire of an electrical wall outlet. If you are going to use a strap with a prong, make sure that you fully understand that the ground¬ing wire in the outlet is the round hole-the other two slots are for electricity, and you do not want to plug your ankle or wrist strap into them! Hint! If you use a wrist strap, make sure that you remove it before working on or near high-voltage components or devices to avoid a potentially deadly situation. Anti-Static Mats Anti-static mats are conductive mats that dissipate ESD They look much like place mats, except they have a small clip attached to them that you can attach to a wrist strap to provide a con¬ductive surface for grounding out ESD. These mats make an excellent place to place your tools and your components when you work on a system. FIGURE 2-2 An anti-static wrist strap grounded to a computer Anti-Static Floor Mats Anti-static floor mats look similar to anti-static mats, and they also have the clip that you can attach to a metal object for the purposes of grounding. The main dif¬ference is that you need to stand on the floor mats to ground yourself and protect against ESD. Anti-Static Bags Placing components in anti-static bags, as mentioned earlier in this chapter, will greatly help your efforts to prevent ESD. Anti-static bags have a special coating or contain small filaments that help dissipate any static charge present when you pick up a component wrapped in such a bag. Better bags resist moisture as well. Always put PC cards and components (drives, RAM, and so on) in anti-static bags. Note that regular plastic or paper bags will not protect your components. In fact, if you put a PC component in a plastic bag, you will almost invariably damage that component. Don't do it! Anti-Static Spray Anti-static spray is normally used to avoid static charges in your clothing. Although many people use these sprays to help protect their work areas from the effects of ESD, it is not recommended. If any of the spray touches your compo¬nents, it could cause damage. Fabric Softener As mentioned earlier in this chapter, a mixture of 1 part fabric softener to 10 parts water is an excellent solution to use on a damp cloth to wipe down the plastic surfaces of your PC and monitor. This can protect them from the harmful effects of static. Potential Dangerous or Hazardous Situations Temperature and the level of humidity outside can dramatically affect the risk of ESD inside. If it's cold and dry outside, like an Alaskan winter, and the heater's blowing inside, you are basically a PC-smoking ZAP! waiting to happen. You need to take precautions. You can protect your system against the effects of ESD by wearing natural fiber clothes (cotton, linen, wool, horsehair) when working on computers. Synthetic fabrics have a tendency to produce static electricity, and you should avoid wearing them. Slinky polyester might be back in style, but save it for the clubs, not the workbench! You should also wear shoes with rubber soles when working on PCs, and have a work area with a linoleum or uncarpeted floor, because walking on rugs and car¬pets can generate a great deal of static electricity. Long hair is another concern when working around computers. If you wear your hair long, you should tie it back before working on a machine so that it does not accidentally get caught or stuck in any components. You should also try to use anti-static smoothing lotions that are now available to reduce the amount of sta¬tic in your hair. If you don't like the anti-static smoothing lotions, hairspray can help to prevent this problem to a certain extent. If you wear rings and other jewelry, you need to remember to remove them before working on a PC, as these can cause electrical current problems. Another risk of wearing jewelry while working inside machines is that a ring may become stuck on pins or components, which can cause cuts and scratches to your fingers or break off the pins of components. Finally, to prevent dangers or hazards to yourself, remove your anti-static wrist strap when working on components with high voltages, and never touch a high ¬voltage device at the same time that you touch a low-voltage device-the two devices could use your body as a conductor to pass electricity. SUMMARY  Objective 2.01: Preventative Maintenance Procedures A solution of mild soap and water dues a great job of cleaning plastic surfaces. You should reg¬ularly inspect and clean the contacts of your components. The contacts get dirty from the oily residue from your fingers, so you should exercise care in handling components. Denatured alcohol is the best solution to use for cleaning drives and contacts.  Objective 2.02: Component Protection and Storage A UPS protects your system against power sags, and surge suppressor protects your system from power surges. In the event of a lightning storm, make sure you completely unplug the PC and any peripherals with external power cords. When storing components for future use, make sure to store them in a cool, dry place in anti-static bags or in their original packaging.  Objective 2.03: Potential Hazards and Proper Safety Procedures The capacitors in PC power supplies, monitors, and laser printers carry very high voltages that can cause severe bodily injuries. Don't touch them inside the cases! This is especially true for CRT monitors, which carry deadly levels of electricity even after being unplugged for days.  Objective 2.04: Special Disposal Procedures and Environmental Guidelines Batteries contain nasty chemicals, CRTs contain lead, and even innocuous seeming toner cartridges have environmentally unfriendly chemicals. Always be sure to recycle batteries, monitors, and tuner car¬tridges, or at least have them picked up as hazardous waste.  Objective 2.05: Electrostatic Discharge Precautions and Procedures To help protect your system from the effects of ESD, always use an anti-static wrist strap or ankle strap. Anti-static mats, floor mats, and sprays can pro¬tect your work area. Chapter 3 Motherboards, Buses and Power supplies At the heart of every personal computer lives certain core components. The motherboard provides the basic structure upon which everything else builds. The expansion bus enables you to add cards (and thus functions) to the PC, ranging from the basics of video and networking to the wildest science-fiction compo¬nents. The power supply provides DC current to feed the motherboard and components and makes everything work. Every good tech needs to understand these three basic parts of the PC, including their common vari¬ants. Ready? Objective 3.01 Common Motherboards: Components and Architecture Every device in your PC connects either directly or indirectly to the mother¬board, the foundation of your computer. Technicians often refer to the moth¬erboard as the systemboard. Both terms are completely interchangeable, and questions on the exam may be worded either way. Motherboards come in several standardized configurations-called form factors¬ - that define the size, location of expansion slots, and so on. Numerous form factors have come and gone, but you need to know about three of them for the A+ exams: AT (Advanced Technology), Baby AT, and ATX (AT Extended). The form factor of your motherboard also determines the type of case you need for your computer. AT motherboards fit into AT cases, and ATX mother¬boards fit into ATX cases. When you replace an AT motherboard with an ATX motherboard, you must also replace the case. Full AT and Baby AT Form Factors AT motherboards were introduced in 1984 and measure 12 x 13 inches. The AT motherboard's processor socket is located near the front of the board. The only integrated port on this motherboard is for the keyboard. All other devices connect to the motherboard via cards and expansion slots. The Baby AT motherboard, shown in Figure 3-1, measures 8.5 x 13 inches and is laid out exactly like the AT motherboard. Through both AT form factor gener¬ations, the location of the screw holes and keyboard port (the same 5-pin DIN socket used as far back as the ancient XT motherboards!) have remained constant, which enables you to fit any AT board into nearly any AT case. FIGURE 3-1 Baby AT motherboard Exam Tip Although vendors sell few AT motherboards today, many systems humming away in offices and homes still have AT motherboards. You need to know about them for common tech work and, consequently, for the A+ Certification exams. AT power supplies connect to the AT or Baby AT motherboard with one P8 connector and one P9 connector. Each connector has two black ground wires that must be kept together with the other connector's black ground wires when the connectors are plugged in. In other words, all four black wires sit together in the center when the plugs are properly inserted. For more information regarding power supplies, refer to Chapter 11. Hint! Keep the black ground wires of the P8 and P9 connectors together or you could damage your motherboard. ATX Intel created the ATX motherboard in 1996. The ATX motherboard, shown in Figure 3-2, measures 12 x 9.6 inches. Although approximately the same size as the Baby AT, the ATX motherboard layout is rotated 90 degrees, and the processor sits near the back of the board. ATX boards commonly have numerous integrated ports, including two serial ports, a parallel port, universal serial bus (USB) ports, and mini-DIN connectors for the keyboard and mouse. In fact, the PS/2 connec¬tors provide one of the quickest visual ways to distinguish between ATX and AT motherboards, because the latter use the larger 5-pin DIN. ATX differs from AT motherboards in a trio of power issues. First, ATX power supplies connect to the motherboard via a single P1 connector, rather than P8 and P9. Second, ATX motherboards implement soft power, a trickle of voltage always on the motherboard so you can set them up to do some cool things, such as acti¬vate the PC over a Network or via a modem. Soft power also enables you to turn off the hardware by shutting down the operating system. Finally, ATX motherboards introduced support for power management controlled by the sys¬tem BIOS. FIGURE 3-2 The ATX motherboard SIMMs and DIMMs Most form factors contain Single Inline Memory Module (SIMM) or Dual Inline Memory Module (DIMM) memory slots; some motherboards designed for the Pentium III and Pentium 4 processors have Rambus Inline Memory Module (RIMM) slots. For more information regarding RAM and memory slots, please refer to Chapter 6. Processor Sockets Every AT, Baby AT, and ATX motherboard has a processor socket or slot to attach a processor to the motherboard. For more information regarding processors and their sockets, please refer to Chapter 5. External Cache Memory CPUs use Level 2 (L2) cache memory to store frequently accessed commands and data. Current CPUs have an L2 cache incorporated into the microprocessor pack¬age, or die, but earlier systems had an L2 cache on the motherboard. Some pre-Pentium systems enabled you to add an L2 cache in slots on the motherboard; early Pentium systems generally had the cache soldered directly on the motherboard. Objective 3.02 Common PC Expansion Buses A bus is a pathway on the motherboard that enables the components to com¬municate with the CPU. The A+ certification exams test you on the common buses, plus you need to know these for day-to-day tech stuff: ISA, EISA, VESA local bus, PCI, AGP, and USB. These acronyms and initials are spelled out and described in the following sections. ISA IBM introduced what became the Industry Standard Architecture (ISA) I/O bus with its first mainstream PC, the 8088. The initial ISA bus was 8-bits wide and offered IRQs 0-7. The 16-bit ISA bus came out in 1984. This newer ISA bus runs at 8.3 MHz and supports IRQs (interrupt requests) 0-15. Although both ISA cards are different sizes, both can be used in a 16-bit ISA slot. Figure 3-3 shows a moth¬erboard with both 8-bit and 16-bit ISA slots. You can still see ISA slots in many computers today that support both 8- and 16-bit cards. Exam Tip The 16-bit ISA slots support the use of either 8-bit or 16-bit ISA cards. FIGURE 3-3 ISA expansion slots EISA Compaq formed the committee that created the Extended Industry Standard Architecture (EISA) as an open standard for bus architecture to compete with IBM's proprietary microchannel architecture (MCA). The EISA bus is 32-bits wide, has an 8.3-MHz bus speed, and supports bus mastering. EISA slots look similar to ISA slots, as you can see in Figure 3-4, and in fact support ISA cards