Page 106 chapter 5 The System Unit

Page 107 RomanR/Shutterstock Why should I read this chapter?

• • • Page 108 Victoria Shapiro/Shutterstock System units are getting smaller, faster, cheaper, and more powerful. These staggering improvements are resulting in microchips integrating with all aspects of our lives. For example, in the future we will see everything from microchips embedded in the brain that improve mental capacity to sensors that can literally read your mind. This chapter covers the things you need to know to be prepared for this ever-changing digital world, including: Types of computers—learn the strengths and weaknesses of cell phones, tablets, laptops, desktops, and wearable computers. Computer components—understand the impact microprocessors and memory have on the power of a computer. Peripherals and upgrades—expand your computer’s abilities and speed. Learning Objectives After you have read this chapter, you should be able to: 1 Differentiate between the five basic types of system units. 2 Describe system boards, including sockets, slots, and bus lines. 3 Recognize different microprocessors, including microprocessor chips and specialty processors. 4 Compare different types of computer memory, including RAM, ROM, and flash memory. 5 Explain expansion cards and slots. 6 Describe bus lines, bus widths, and expansion buses. 7 Describe ports, including standard and specialized ports. 8 Identify power supplies for cell phones, tablets, laptops, and desktops. 9 Explain how a computer can represent numbers and encode characters electronically. Introduction “Hi, I’m Liz, and I’m a computer technician. I’d like to talk with you about the

different types of system units for personal computers. I’d also like to talk about various electronic components that make your computer work.” wavebreakmedia/Shutterstock Why are some computers more powerful than others? The answer lies in three words: speed, capacity, and flexibility. After reading this chapter, you will be able to judge how fast, powerful, and versatile a particular personal computer is. As you might expect, this knowledge is valuable if you are planning to buy a new personal computer system or to upgrade an existing system. (The Computer Buyer’s Guide at the end of this book provides additional information.) This knowledge will help you evaluate whether or not an existing system is powerful enough for today’s new and exciting applications. Sometime you may get the chance to watch when a technician opens up a personal computer. You will see that it is basically a collection of electronic circuitry. Although there is no need to understand how all these components work, it is important to understand the principles. Armed with this knowledge, you will be able to confidently make sound purchasing and upgrading decisions. To efficiently and effectively use computers, you need to understand the functionality of the basic components in the system unit, including the system board, microprocessor, memory, expansion slots and cards, bus lines, ports, cables, and power supply units. System Unit The system unit, also known as the system chassis, is a container that houses most of the electronic components that make up a computer system. Some system units are located in a separate case, whereas others share a case with other parts of the computer system. As we have previously discussed, a personal computer is the most widely used type of computer. It is the most affordable and is designed to be operated directly by an end user. The five most common types are cell phones, tablets, laptops, desktops, and wearable computers. Each has a unique type of system unit.

Page 109 ethics Many of the electronic devices purchased in the United States are manufactured in other countries. Some of these manufacturers pay extremely low wages, have unsafe or unacceptable work conditions, and pollute local environments. Do you think that consumers have an ethical responsibility regarding where and/or how products are manufactured? Smartphones As we discussed in Chapter 1, almost everyone has a cell phone, and almost every cell phone is a smartphone. Smartphones are the most popular type of personal computer. They are effectively a thin slab that is almost all monitor, with the system unit, secondary storage, and all electronic components located behind the monitor. Designed to comfortably fit into the palm of one hand and accept finger touches on the monitor as the primary input, cell phones have become the indispensable handheld computer. (See Figure 5-1.) Figure 5-1 Cell phone Alexey Boldin/Shutterstock Tablets Tablets, also known as tablet computers, are very similar to cell phones, although tablets are larger, heavier, and generally more powerful. Also, a tablet is not designed to be used as a phone and, typically, cannot be connected to phone networks. Mini tablets are a type of tablet with a smaller screen. Although mini tablets operate like a traditional tablet, they typically do not have all the functionality of the bigger tablets. Their most significant advantage is that they are easier to transport in pockets and purses. (See Figure 5-2.)

Figure 5-2 Mini tablet Apple/ZUMA Press/Newscom Laptops Like cell phones and tablets, laptops have their system units housed with selected secondary storage and input devices. Laptops, however, are larger and more powerful. Their larger monitor is separate from the rest of the computer and attached to the system unit with a hinge. Unlike cell phones and tablets, most laptops do not accept input by touching the screen. Rather, laptops typically use an attached keyboard and a mouse as the primary input devices. There are several specialized laptops with features that make them unique. Some of them are • Two-in-one laptops, which include a touch screen and the ability to fold flat like a tablet computer. These laptops offer the advantages of a laptop with the convenience of a tablet. (See Figure 5-3.) • Gaming laptops, which include high-end graphics hardware and very fast processors. As laptops have become more powerful, gaming laptops have become a favorite, primarily due to their portability. To learn more about specialized gaming computers, see the Making IT Work for You: Gaming on pages 110 and 111. • Ultrabooks, also known as ultraportables or mini notebooks, are lighter and thinner with longer battery life than most laptops. They accomplish these advantages by leaving out components such as optical drives and using energy-efficient microprocessors. (See Figure 5-4.)

Figure 5-3 Two-in-one laptop Lukmanazis/Shutterstock Figure 5-4 Ultrabook manaemedia/Shutterstock Desktops Desktops are the most powerful type of personal computer. Like cell phones and tablets, some desktop computers, like Apple’s iMac, have their monitor and system unit housed together in the same case. These computers are known as all-in-one desktops. (See Figure 5- 5.) Figure 5-5 All-in-one desktop Microsoft/UPI/Newscom However, most desktops have their system unit in a separate case. This case contains the system’s electronic components and selected secondary storage devices. Input and output devices, such as a mouse, keyboard, and monitor, are located outside the system unit. This type of system unit is designed to be placed either horizontally or vertically. Desktop system units that are placed vertically are sometimes referred to as a tower unit or tower computer. (See Figure 5-6.)

Page 110 Figure 5-6 Tower unit Mmaxer/Shutterstock Making IT work for you | GAMING Have your friends been playing a new game together and you would like to join? Would you like to play video games but don’t know where to start? You can use a cell phone to play video games anywhere, you can use gaming consoles to play the latest titles in your living room, and you can use PC gaming computers to play the highest-quality games ever developed. It is easy to find the right game for you, once you understand the different gaming platforms and the types of games available. Mobile Gaming Many people are unaware that their cell phone is a powerful gaming device. Mobile devices, like cell phones and tablets, offer exciting game-play experiences on the go. Casual gaming—Mobile games are often designed to be “casual games,” meaning the games are easy to pick up and play in short bursts. This is ideal for someone who wants to play for a few minutes while waiting in line or taking a break from work. Popular examples of casual gaming are Words with Friends and Angry Birds. Augmented reality—More sophisticated mobile games use the mobile device’s GPS and camera to create “augmented reality” multiplayer games, where the game’s graphics are a mixture of video images from the phone’s camera and fantasy elements in the game realm. Examples of these games are Pokémon Go and Google’s Ingress. Hidden costs—A final word of caution on mobile games: many are free to play, but there may be hidden costs you should be aware of. Some games require high data usage that can rack up charges on your phone bill, and some may try to access personal information on your phone that you don’t intend to share. Be aware of your data usage, read any fine print, and exercise caution when a game asks for credit card information or permission to access data on your phone.

Page 111 Minecraft and other mobile games are designed to take advantage of cell phone and tablet interfaces. Volodymyr Kalyniuk/Shutterstock Console Gaming The most popular video game hardware isn’t a desktop or laptop computer. It is a specialized computer called a gaming console. Consoles have specialized hardware that produce high-quality graphics and sound and are designed to take advantage of TVs and home theaters. They provide wireless controllers for playing from the living room couch and HDMI ports to support standard TV resolutions and sound configurations. Also, because consoles are standardized and popular, they often have large libraries of games to choose from. The three most popular consoles are Nintendo Switch, Microsoft Xbox One, and the Sony PlayStation 4. If you are looking for an immersive video game that goes beyond the casual gamer experience, consoles offer great performance at a reasonable price with excellent online features and gaming libraries. Here are a few things to consider when deciding what console to purchase: Friends—If you want to play online games with your friends, you will need to get the same console that your friends have. If you want to play games when friends come over to visit, Nintendo offers many of the most innovative cooperative games with an emphasis on party games meant to be played together simultaneously. Input devices—Each console has its own controllers, with different strengths and weaknesses. Nintendo offers motion-control controllers that use hand gestures to play games, Sony has a virtual reality headset, and Microsoft has a sophisticated set of cameras that can record body position and motion. Games—Although many games are offered across all consoles, some are exclusive to only one console. Further, each console has types of games that they are best known for. Nintendo, for example, tends to attract more casual and family-friendly gamers, whereas the Xbox is famous for its intense online competition. Look for a console with a catalog of games that appeal to you.

Page 112 Sony’s PlayStation VR with PS VR headset. Each console has its own unique input/output devices. Kazuo Horiike/Jiji Press/Newscom PC Gaming While mobile devices and console systems are the most common and popular gaming devices, gaming desktops and laptops offer unparalleled experiences that attract video games’ biggest fans. Gaming PCs offer the highest degree of customizability, with specialized graphics cards and input devices. Although an entry-level gaming desktop isn’t much more expensive than a typical desktop, the price can quickly escalate as you approach the cutting edge of graphics and sound technology. Here are some things to consider before buying a gaming PC: Indy games—Beyond offering the highest-quality video game experience, gaming PCs also have access to niche and independent (indy) video game developers, who cannot easily release games on consoles or mobile devices. Upgrades—Desktop PCs allow the computer hobbyist to upgrade hardware as technology improves. Gamers who are willing to open up their computer and replace parts can keep their gaming PC playing the newest games without having to buy a whole new computer. Compatibility—The fact that PC hardware is so customizable can make it difficult to be sure that the game you purchase is compatible with your PC configuration. PC gamers must know their system specifications when buying video games to be sure that the game will run on their system.

A powerful gaming PC includes specialized hardware for running high- performance graphics. Gorodenkoff/Shutterstock Wearable Computers Wearable computers, also known as wearable devices, are one of the first evolutionary steps to the Internet of Things (IOT), as discussed in Chapter 2. These devices contain an embedded computer on a chip that is typically much smaller and less powerful than a cell phone’s. The most common wearable computers are smartwatches and activity trackers. (See Figure 5-7.) Figure 5-7 Smartwatch charnsitr/Shutterstock • Smartwatches like Apple’s Watch. This device acts as a watch, fitness monitor, and communication device. For example, the Apple Watch connects to an iPhone to display e-mails, text messages, and calendar reminders on the user’s wrist. • Activity trackers like Fitbit’s Flex 2. This device monitors daily exercise and sleep patterns. It also connects wirelessly to desktops, laptops, and smartphones to record and share data.

Page 113 Components Personal computers come in a variety of different sizes, shapes, and capabilities. Although they look different and each has its own unique features, they share surprisingly similar components, including system boards, microprocessors, and memory. (See Figure 5-8.) Figure 5-8 System unit components Cell phone: Reprinted with permission from iFixit; Tablet: Reprinted with permission from iFixit; Wearable: Bill Detwiler/TechRepublic. Used with permission of TechRepublic.com Copyright©2019. All rights reserved; Laptop: Bill Detwiler/TechRepublic. Used with permission of TechRepublic.com Copyright©2019. All rights reserved; Desktop: Godfried Edelman/iStock/Getty Images concept check What is the system unit? Describe and compare the five most common types of personal computers. What is an ultrabook? What is an all-in-one? What is a tower unit? What is a mini tablet?

Page 114 System Board The system board is also known as the mainboard or motherboard. The system board controls communications for the entire computer system. All devices and components connect to the system board, including external devices like keyboards and monitors and internal components like hard drives drives and microprocessors. The system board acts as a data path and traffic monitor, allowing the various components to communicate efficiently with one another. For cell phones, tablets, and wearable computers, the system board is located behind the screen. For laptops and desktops, the system board is typically located at the bottom of the system unit or along one side. It is a flat circuit board covered with a variety of different electronic components, including sockets, slots, and bus lines. (See Figure 5-9.) Figure 5-9 Desktop system board Branston/Future/REX/Shutterstock • Sockets provide a connection point for small specialized electronic parts called chips. Chips consist of tiny circuit boards etched onto squares of sandlike material called silicon. These circuit boards can be smaller than the tip of your finger. (See Figure 5- 10.) A chip is also called a silicon chip, semiconductor, or integrated circuit. Chips typically are mounted onto chip carriers. (See Figure 5-11.) These carriers plug either directly into sockets on the system board or onto cards that are then plugged into slots on the system board. Sockets are used to connect the system board to a variety of different types of chips, including microprocessor and memory chips. • Slots provide a connection point for specialized cards or circuit boards. These cards provide expansion capability for a computer system. For example, a wireless networking card plugs into a slot on the system board to provide a connection to a local area network.

• Connecting lines called bus lines provide pathways that support communication among the various electronic components that are either located on the system board or attached to the system board. Figure 5-10 Chip Lucidio Studio Inc/Photographer’s Choice/Getty Images Figure 5-11 Chip mounted onto a chip carrier Geostock/Getty Images Generally, the system board found on a desktop is larger than that found on a laptop, and much larger than one found on a tablet, cell phone, or wearable computer. Although these system boards vary in size, speed, power, and versatility, they nevertheless all perform the same function of communicating between the components of the personal computer. environment Have you ever wondered what you should do with your old computers, monitors, and mobile devices? If you were to simply throw them out, the dangerous chemicals used to manufacture these devices can end up polluting our air, soil, and water. First, consider donating them to various charitable organizations that work with local schools and low- income families. Otherwise, recycle them. Many computer retailers near you accept

Page 115 used devices and components for recycling, even if they are broken. Alternatively, visit the website of your local government to find the electronics recycling center nearest you. concept check What is the system board, and what does it do? Define and describe sockets, slots, and bus lines. What are chips? How are chips attached to the system board? Microprocessor In most personal computer systems, the central processing unit (CPU) or processor is contained on a single chip called the microprocessor. The microprocessor is the “brains” of the computer system. It has two basic components: the control unit and the arithmetic-logic unit. • Control unit: The control unit tells the rest of the computer system how to carry out a program’s instructions. It directs the movement of electronic signals between memory, which temporarily holds data, instructions, and processed information, and the arithmetic-logic unit. It also directs these control signals between the CPU and input and output devices. • Arithmetic-logic unit: The arithmetic-logic unit, usually called the ALU, performs two types of operations: arithmetic and logical. Arithmetic operations are the fundamental math operations: addition, subtraction, multiplication, and division. Logical operations consist of comparisons such as whether one item is equal to (=), less than (<), or greater than (>) the other. Microprocessor Chips Chip processing capacities are often expressed in word sizes. A word is the number of bits (such as 32 or 64) that can be accessed at one time by the CPU. The more bits in a word, the more data a computer can process at one time. Eight bits group together to form a byte. A 32-bit-word computer can access 4 bytes at a time. A 64-bit-word computer can access 8 bytes at a time. Therefore, the computer designed to process 64-bit words has greater processing capacity. Other factors affect a computer’s processing capability, including how fast it can process data and instructions. The processing speed of a microprocessor is typically represented by its clock speed, which is related to the number of times the CPU can fetch and process data or instructions in a second. Older personal computers typically process data and instructions in millionths of a

second, or microseconds. Newer personal computers are much faster and process data and instructions in billionths of a second, or nanoseconds. Supercomputers, by contrast, operate at speeds measured in picoseconds—1,000 times as fast as personal computers. In the near future, we can expect processor speeds to be 1,000 times faster than that, operating at speeds measured in femtoseconds. (See Figure 5-12.) Logically, the higher a microprocessor’s clock speed, the faster the microprocessor. However, some processors can handle multiple instructions per cycle or tick of the clock; this means that clock speed comparisons can only be made between processors that work the same way. Figure 5-12 Processing speeds At one time, personal computers were limited by microprocessors that could support a single CPU that controlled operations. These computers were limited to processing one program at a time. Now, many personal computers have multicore processors that can provide two or more separate and independent CPUs. For example, a quad-core processor could have one core computing a complex Excel spreadsheet, a second core creating a report using Word, a third core locating a record using Access, and a fourth core running a multimedia presentation—all at the same time. More significantly, however, is the potential for personal computers to run very large, complex programs that previously required expensive and specialized hardware. For multicore processors to be used effectively, computers must understand how to divide tasks into parts that can be distributed across each core—an operation called parallel processing. Operating systems such as Windows 10 and macOS Mojave support parallel processing. Software developers use this technology for a wide range of applications from scientific programs to sophisticated computer games. See Figure 5-13 for a table of popular microprocessors. Figure 5-13 Popular microprocessors Specialty Processors In addition to microprocessor chips, a variety of more specialized processing chips have been developed and are widely used. For example, many cars have more than 100 separate

Page 116 specialty processors to control nearly everything from fuel efficiency to satellite entertainment and tracking systems. Coprocessors, one of the more popular specialty processors, are specialty chips designed to improve specific computing operations. For example, to support fast processing of virtual environments, a standard feature in gaming computers is a graphics coprocessor known as a GPU (graphics processing unit). These processors are designed to handle a variety of specialized tasks such as displaying 3D images and encrypting data. Most cell phones and tablets have specialty processors to efficiently show and store videos. concept check Name and describe the two components of a microprocessor. Define word, clock speed, multicore chip, and parallel processing. What are specialty processors? Describe coprocessors. What is a GPU? privacy Did you know that one type of specialty processor is devoted exclusively to protecting your privacy? Called cryptoprocessors, these microchips perform encoding and decoding of data faster and more securely than a CPU. These specialized chips exist in ATMs, TV set-top boxes, and credit card machines. Memory Memory is a holding area for data, instructions, and information. Like microprocessors, memory is contained on chips connected to the system board. There are three well-known types of memory chips: random-access memory (RAM), read-only memory (ROM), and flash memory. RAM Random-access memory (RAM) chips hold the program (sequence of instructions) and data that the CPU is presently processing. (See Figure 5-14.) RAM is called temporary or volatile storage because everything in most types of RAM is lost as soon as the computer is turned off. It is also lost if there is a power failure or other disruption of the electric current going to the computer. Secondary storage, which we shall describe in Chapter 7, does not lose its contents. It is permanent or nonvolatile storage, such as the data stored on a hard disk. For this reason, as we mentioned earlier, it is a good idea to frequently save your work in progress to a secondary storage device. That is, if you are working on a document or a spreadsheet, every few minutes you should save, or store, the material.

Figure 5-14 RAM chips mounted on circuit board Simon Belcher/Alamy Stock Photo Cache (pronounced “cash”) memory improves processing by acting as a temporary high- speed holding area between the memory and the CPU. The computer detects which information in RAM is most frequently used and then copies that information into the cache. When needed, the CPU can quickly access the information from the cache. Having enough RAM is important! For example, to use the standard version of Microsoft Office 365, you need 4 GB, or 4 billion bytes, of RAM. Some applications, such as photo editing software, may require even more. Fortunately, additional RAM can be added to a computer system by inserting an expansion module called a DIMM (dual in-line memory module) into the system board. The capacity or amount of RAM is expressed in bytes. There are three commonly used units of measurement to describe memory capacity. (See Figure 5- 15.) Figure 5-15 Memory capacity Even if your computer does not have enough RAM to hold a program, it might be able to run the program using virtual memory. Most of today’s operating systems support virtual memory. With virtual memory, large programs are divided into parts, and the parts are stored on a secondary device, usually a hard disk. Each part is then read into RAM only when needed. In this way, computer systems are able to run very large programs. ROM Read-only memory (ROM) chips have information stored in them by the manufacturer. Unlike RAM chips, ROM chips are not volatile and cannot be changed by the user. “Read only” means that the CPU can read, or retrieve, data and programs written on the ROM chip. However, the computer cannot write—encode or change—the information or instructions in

Page 117 ROM. Not long ago, ROM chips were typically used to contain almost all the instructions for basic computer operations. For example, ROM instructions are needed to start a computer, to access memory, and to handle keyboard input. Recently, however, flash memory chips have replaced ROM chips for many applications. Flash Memory Flash memory offers a combination of the features of RAM and ROM. Like RAM, it can be updated to store new information. Like ROM, it does not lose that information when power to the computer system is turned off. Flash memory is used for a wide range of applications. For example, it is used to store the start-up instructions for a computer. This information is called the system’s BIOS (basic input/output system). This information includes the specifics concerning the amount of RAM and the type of keyboard, mouse, and secondary storage devices connected to the system unit. If changes are made to the computer system, these changes are reflected in flash memory. See Figure 5-16 for a summary of the three types of memory. Figure 5-16 Memory concept check What is memory? Name and describe three types. What are cache memory, DIMM, and virtual memory? Define ROM and flash memory. Expansion Cards and Slots To meet the size constraints of cell phones, tablets, and laptops, fingernail-size expansion cards known as SD cards have been developed. These cards plug into expansion slots located within many cell phones, tablets, and laptops. (See Figure 5-17.)

Figure 5-17 SD card Vitalii Petrushenko/Shutterstock As previously mentioned, many personal computers allow users to expand their systems by providing expansion slots on the system board. Users can insert optional devices known as - expansion cards into these slots. (See Figure 5-18.) Ports on the cards allow cables to be connected from the expansion cards to devices outside the system unit. (See Figure 5-19.) There are a wide range of different types of expansion cards. Some of the most commonly used expansion cards are Figure 5-18 Expansion cards fit into slots on the system board Piotr Adamowicz/Shutterstock Figure 5-19 Expansion card with three ports antpkr/Shutterstock • Graphics cards, which provide high-quality 3D graphics and animation for games and simulations. While many personal computer systems have a GPU connected directly to the system board, others connect through a graphics card. This card can contain one or more GPU chips and is standard for most gaming computers.

Page 118 • Network interface cards (NIC), also known as network adapter cards, are used to connect a computer to a network. (See Figure 5-20.) The network allows connected computers to share data, programs, and hardware. The network adapter card connects the system unit to the network via a network cable. • Wireless network cards allow computers to be connected without cables. As we will discuss in Chapter 8, wireless networks in the home are widely used to share a common Internet connection. Each device on the network is equipped with a wireless network card that communicates with the other devices. Figure 5-20 Network interface card CobraCZ/Shutterstock concept check List and describe three commonly used expansion cards. What are SD cards? How are they used? What are expansion slots and cards? What are they used for? Bus Lines As mentioned earlier, a bus line—also known simply as a bus—connects the parts of the CPU to each other. Buses also link the CPU to various other components on the system board. (See Figure 5-21.) A bus is a pathway for bits representing data and instructions. The number of bits that can travel simultaneously down a bus is known as the bus width.

Figure 5-21 Bus is a pathway for bits Stockbyte/Getty Images A bus is similar to a multilane highway that moves bits rather than cars from one location to another. The number of traffic lanes determines the bus width. A highway (bus line) with more traffic lanes (bus width) can move traffic (data and instructions) more efficiently. For example, a 64-bit bus can move twice as much information at a time as a 32-bit bus. Why should you even care about what a bus line is? Because as microprocessor chips have changed, so have bus lines. Bus design or bus architecture is an important factor relating to the speed and power for a particular computer. Additionally, many devices, such as expansion cards, will work with only one type of bus. Every computer system has two basic categories of buses. One category, called system buses, connects the CPU to memory on the system board. The other category, called expansion buses, connects the CPU to other components on the system board, including expansion slots. Expansion Buses Computer systems typically have a combination of different types of expansion buses. The principal types are USB, FireWire, and PCIe. • Universal serial bus (USB) is widely used today. External USB devices are connected from one to another or to a common point or hub and then onto the USB bus. The USB bus then connects to the PCI bus on the system board. The current USB standard is USB 3.2. • FireWire buses are similar to USB buses but are more specialized. They are used primarily to connect audio and video equipment to the system board. • PCI Express (PCIe) is widely used in many of today’s most powerful computers. Unlike most other buses that share a single bus line or path with several devices, the PCIe bus provides a single dedicated path for each connected device.

Page 119 concept check What is a bus, and what is bus width? What is the difference between a system and an expansion bus? Discuss three types of expansion buses. Ports A port is a socket for external devices to connect to the system unit. A cell phone typically uses a port to recharge its battery. (See Figure 5-22.) Some ports connect directly to the system board, while others connect to cards that are inserted into slots on the system board. Some ports are standard features of most computer systems, and others are more specialized. (See Figure 5-23.) Figure 5-22 Cell phone port SlayStorm/Shutterstock

Figure 5-23 Ports oleschwander/Shutterstock Standard Ports Most desktop and laptop computers come with a standard set of ports for connecting peripherals, or external devices, such as a monitor and keyboard. The most common ports are: • Universal serial bus (USB) ports can be used to connect several devices to the system unit and are widely used to connect keyboards, mice, printers, storage devices, and a variety of specialty devices. There are many types of USB ports. USB-A is the port found on most laptops and desktops. USB-B ports are found on peripheral devices, like digital cameras and cell phones. The newest USB type, USB-C, is gaining popularity on cell phones and laptops. It is expected to replace USB-A and USB-B in the future. USB-C is faster, more powerful, and smaller than previous USB types. A single USB port can be used to connect many USB devices to the system unit. • High Definition Multimedia Interface (HDMI) ports provide high-definition video and audio, making it possible to use a computer as a video jukebox or an HD video recorder. • Thunderbolt ports, first introduced in Apple’s MacBook Pro computer, provide high- speed connections. A single port can connect up to seven separate devices connected one to another. Thunderbolt ports promise to replace a number of different types of ports, including Mini DisplayPorts. • Ethernet ports are a high-speed networking port that has become a standard for many of today’s computers. Ethernet allows you to connect multiple computers for sharing

Page 120 files, or to a DSL or cable modem for high-speed Internet access. Specialized Ports In addition to standard ports, there are numerous specialty ports. The most common include: • Mini DisplayPort (MiniDP or mDP) ports are audiovisual ports typically used to connect large monitors. These ports are used with many Apple Macintosh computers. • VGA (Video Graphics Adapter) and DVI (Digital Video Interface) ports provide connections to analog and digital monitors, respectively. DVI has become the most commonly used standard, but VGA ports are still provided on almost all systems for compatibility with older/lower-cost monitors. • FireWire ports provide high-speed connections to specialized FireWire devices such as camcorders and storage devices. Cables Cables are used to connect exterior devices to the system unit via the ports. One end of the cable is attached to the device, and the other end has a connector that is attached to a matching connector on the port. Standard cables include USB, HDMI, Thunderbolt, and Ethernet. (See Figure 5-24.) Figure 5-24 Standard cables USB: Dino Osmic/Shutterstock; HDMI: nikitabuida/Getty Images; Thunderbolt: Chris Willson/Alamy Stock Photo; Ethernet: Kamolrat/Shutterstock Power Supply Computers require direct current (DC) to power their electronic components and to represent data and instructions. DC power can be provided indirectly by converting alternating current

(AC) from standard wall outlets or directly from batteries. • Most cell phones and tablets are powered directly from batteries that are recharged using an AC adapter. These adapters plug into standard wall outlets and convert AC to DC. With cell phones and tablets, a USB cable often connects the AC adapter to the mobile device. Some cell phones, however, can use a wireless charging platform, eliminating the cable. (See Figure 5-25.) Most tablets, mobile devices, and wearable computers can operate only using battery power. Their AC adapters or charging platforms are only used to recharge batteries. • Like cell phones and tablets, laptops typically use AC adapters that are located outside the system unit. (See Figure 5-26.) Unlike cell phones and tablets, these computers can be operated either using an AC adapter plugged into a wall outlet or using battery power. Their batteries typically provide sufficient power for up to eight hours before they need to be recharged. • Desktop computers have a power supply unit located within the system unit. (See Figure 5-27.) This unit plugs into a standard wall outlet, converts AC to DC, and provides the power to drive all of the system unit components. Unlike cell phones, tablets, or laptops, desktop computers do not have batteries and cannot operate unless connected to a power source. Figure 5-25 Wireless charging platform Akkraraj kangrang/Shutterstock

Page 121 Figure 5-26 AC adapter SNP_SS/Shutterstock Figure 5-27 Power supply unit Microstocker13/Shutterstock tips Does your laptop seem to be losing its charge sooner than it used to? These batteries do lose power over time; however, you can take some steps to slow down the aging process. Balance adapter and battery use. The best practice is to use the laptop on battery power for a little while without draining it completely (20 percent charge, for example), followed by charging it back to 100 percent. Modern batteries should not be drained to 0 percent each day. Calibrate it. Your laptop’s manufacturer will recommend that you calibrate, or reset, your battery every few months. Follow its guidelines on the web or in your instruction manual, as it will ensure that the battery meter in your operating system is accurate and that you are getting the expected charge time. Avoid excessive heat. High temperatures can accelerate the deterioration of modern batteries. Therefore, avoid exposure to excessive heat and consider purchasing a laptop cooler or fan. Proper storage. If you are not going to use your laptop for a few weeks, most manufacturers recommend that you remove the battery. concept check What are ports? What do they do? Describe four standard ports and three specialized ports. What is a power supply unit? AC adapter? Charging platform? Electronic Data and Instructions

Page 122 Have you ever wondered why it is said that we live in a digital world? It’s because computers cannot recognize information the same way you and I can. People follow instructions and process data using letters, numbers, and special characters. For example, if we wanted someone to add the numbers 3 and 5 together and record the answer, we might say “please add 3 and 5.” The system unit, however, is electronic circuitry and cannot directly process such a request. Our voices create analog, or continuous, signals that vary to represent different tones, pitches, and volume. Computers, however, can recognize only digital electronic signals. Before any processing can occur within the system unit, a conversion must occur from what we understand to what the system unit can electronically process. tips Is your cell phone struggling to make it through the day on a single charge? Before you replace the battery, consider the following suggestions. Monitor power usage. Some apps are always running, even when you aren’t using your cell phone. To monitor what apps are using the most power, check out the power usage features in your mobile OS and close the apps you are not using. • For Android cell phones: Click on the Settings icon from the home screen, then choose Device, then Battery or Settings, then Power, and finally Battery. • For iOS cell phones: Click on the Settings icon from the Home screen, then choose Battery. Reduce screen brightness. One of the greatest drains on your cell phone’s battery is the monitor. By reducing screen brightness, you can greatly extend your battery life. • For Android cell phones: Swipe down from the top of the screen to display the notification shade and then adjust the brightness slider (an icon that looks like a sun) to lower your screen brightness. • For iOS cell phones: Swipe down from the top right corner of the screen to display the control center and then adjust the brightness bar (an icon that looks like a sun) to lower your screen brightness. Reduce background services. When your battery gets low, you can set your cell phone to reduce its battery usage by performing background processes less frequently. • For Android: Swipe down from the top of the screen to display the notification shade and tap the Battery Saver button. • For iOS cell phones: Click on the Settings icon from the Home screen and choose Battery and tap the Low Power Mode button.

Numeric Representation What is the most fundamental statement you can make about electricity? It is simply this: It can be either on or off. Indeed, many forms of technology can make use of this two-state on/off, yes/no, present/absent arrangement. For instance, a light switch may be on or off, or an electric circuit open or closed. A specific location on a tape or disk may have a positive charge or a negative charge. This is the reason, then, that a two-state or binary system is used to represent data and instructions. The decimal system that we are all familiar with has 10 digits (0, 1, 2, 3, 4, 5, 6, 7, 8, 9). The binary system, however, consists of only two digits—0 and 1. Each 0 or 1 is called a bit —short for binary digit. In the system unit, the 1 can be represented by a negative charge and the 0 by no electric charge. In order to represent numbers, letters, and special characters, bits are combined into groups of eight called bytes. Whenever you enter a number into a computer system, that number must be converted into a binary number before it can be processed. Any number can be expressed as a binary number. Binary numbers, however, are difficult for humans to work with because they require so many digits. Instead, binary numbers are often represented in a format more readable by humans. The hexadecimal system, or hex, uses 16 digits (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F) to represent binary numbers. Each hex digit represents four binary digits, and two hex digits are commonly used together to represent 1 byte (8 binary digits). (See Figure 5-28.) You may have already seen hex when selecting a color in a website design or drawing application, or when entering the password for access to a wireless network.

Figure 5-28 Numeric representations Character Encoding As we’ve seen, computers must represent all numbers with the binary system internally. What about text? How can a computer provide representations of the nonnumeric characters we use to communicate, such as the sentence you are reading now? The answer is character encoding schemes or standards. Character encoding standards assign a unique sequence of bits to each character. Historically, personal computers used the ASCII (American Standard Code for Information Interchange) to represent characters, while mainframe computers used EBCDIC (Extended Binary Coded Decimal Interchange Code). These schemes were quite effective; however, they are limited. ASCII, for example, only uses 7 bits to represent each character, which means that only 128 total characters could be represented. This was fine for most characters in the English language but was not large enough to support other languages such as Chinese and Japanese. These languages have too many characters to be represented by the 7-bit ASCII code. The explosion of the Internet and subsequent globalization of computing have led to a new character encoding called Unicode, which uses 16 bits. The Unicode standard is the most widely used character encoding standard and is recognized by virtually every computer system. The first 128 characters are assigned the same sequence of bits as ASCII to maintain compatibility with older ASCII-formatted information. However, Unicode uses a variable number of bits to represent each character, which allows non-English characters and special

Page 123 Page 124 characters to be represented. concept check What is the difference between an analog and a digital signal? What are decimal and binary systems? How are they different? Compare EBCDIC, ASCII, and Unicode. Careers in IT “Now that you know about system units, I’d like to tell you about my career as a computer technician.” wavebreakmedia/Shutterstock Computer technicians repair and install computer components and systems. They may work on everything from personal computers and mainframe servers to printers. Some computer technicians are responsible for setting up and maintaining computer networks. Experienced computer technicians may work with computer engineers to diagnose problems and run routine maintenance on complex systems. Job growth is expected in this field as computer equipment becomes more complicated and technology expands. Employers look for those with certification or an associate’s degree in computer repair. Computer technicians also can expect to continue their education to keep up with technological changes. Good communication skills are important in this field. Computer technicians can expect to earn an annual salary in the range of $27,000 to $49,000. Opportunities for advancement typically come in the form of work on more advanced computer systems. Some computer technicians move into customer service positions or go into sales. A LOOK TO THE FUTURE

Page 125 Brain–Computer Interfaces Can you imagine a future when we become half human and half machine? Today we use computer implants to help people hear and to control their heartbeat. Computer chips are being implanted into people with Parkinson’s disease to help them control their movements and to reduce other impacts of the condition. But these devices are simple compared to the future of brain–computer interfaces imagined by the researchers and entrepreneurs of Silicon Valley. The human brain stores information in neurons using electrical impulses. Using neural imaging, specialized equipment can read the intensity and location of these impulses or thought patterns. This technology currently allows amputees to control robotic limbs. This case and almost all other applications, however, require brain surgery and cumbersome equipment. Researchers are currently trying to reduce the size and invasiveness of these technologies. Scientists at Florida International University are investigating devices so small that they can travel through the bloodstream to the brain. In the future, a simple shot may allow your computer to tell what you are thinking. With improvements in the quality of neural imaging and neural hardware, we may soon be able to image all the brain’s electrical impulses. For example, when you think of turning on the house lights, a computer can take an image of your brain thinking about turning on the house lights. Later, when you have that thought again, the computer can compare your brain’s image to previous images and realize that when those areas of the brain are active, you want the house lights to turn on. Not only may computers someday read your mind—they someday may write to it as well. Memories are stored in the electrical impulses of the brain, and by injecting tiny magnetic particles into the brain, scientists can stimulate neurons, essentially creating memories. Currently, our understanding of how the brain operates is too limited, and our ability to manipulate neurons is too coarse, to allow us to accurately transmit information. However, someday you may think, “I would like to be able to speak French,” and through neural stimulation, a computer would generate the memories necessary for you to speak French. Many ethicists are concerned by the potential use of such technologies to improve human abilities instead of treating medical conditions. For example, with tiny chips being able to store so much, people could use brain implants to improve their memory. This can lead to a variety of scenarios where the individual with the implants would have an advantage over those who don’t have them. However, others disagree, arguing that the integration of technology and biology is to be expected and it is nothing more than the next step in human evolution. If such a technology became widespread and affordable, would you opt to receive a chip implant?

Victoria Shapiro/Shutterstock VISUAL SUMMARY The System Unit SYSTEM UNIT Lukmanazis/Shutterstock System unit (system chassis) contains electronic components. The most common personal computers are cell phone, tablet, laptop, desktop, and wearable computers. Smartphones Smartphones, more commonly called cell phones, are the most popular personal computer. Amost all monitor with system unit, storage, and electronics located behind monitor. Tablet Tablet, tablet computer, like a cell phone except larger, heavier, and more powerful. A minitablet has a smaller screen with less functionality than traditional tablet. Laptop

Laptops, compared to cell phones are larger, are more powerful, have separate monitor, use keyboard and mouse. Specialty laptops include two-in-one laptops; gaming laptops (high-end graphics and fast processors); ultrabooks, also known as ultraportables; and mini notebooks. Desktop Desktop is most powerful personal computer; tower unit (tower computer) has vertical system unit; all-in-one desktop combines system unit and monitor. Wearable Computers Wearable computers (wearable devices) contain an embedded computer on a chip. The most common wearable computers are smartwatches and activity trackers. Components Each type of system unit has the same basic components, including system board, microprocessor, and memory. SYSTEM BOARD Branston/Future/REX/Shutterstock The system board (mainboard or motherboard) controls all communication for the computer system. All external and internal devices and components connect to it. • Sockets provide connection points for chips (silicon chips, semiconductors, integrated circuits). Chips are mounted on chip carriers. • Slots provide connection points for specialized cards or circuit boards. • Bus lines provide pathways to support communication.

Page 126 Geostock/Getty Images To efficiently and effectively use computers, you need to understand the functionality of the basic components in the system unit: system board, microprocessor, memory, expansion slots and cards, bus lines, ports, and cables. Additionally, you need to understand how data and programs are represented electronically. MICROPROCESSOR In most personal computers, the central processing unit (CPU) or processor is contained on a single chip called the microprocessor. It has two basic components: a control unit and ALU. Microprocessor Chips A word is the number of bits that can be accessed by the microprocessor at one time. Clock speed represents the number of times the CPU can fetch and process data or instructions in a second. Multicore processors can provide multiple independent CPUs. Parallel processing requires programs that allow multiple processors to work together to run large complex programs. Specialty Processors Specialty processors include graphics coprocessors, also known as GPU or graphics processing unit (processes graphic images), and processors in automobiles (monitor fuel efficiency, satellite entertainment, and tracking systems). MEMORY Memory holds data, instructions, and information. There are three types of memory chips. RAM

RAM (random-access memory) chips are called temporary or volatile storage because their contents are lost if power is disrupted. • Cache memory is a high-speed holding area for frequently used data and information. • DIMM (dual in-line memory module) is used to expand memory. • Virtual memory divides large programs into parts that are read into RAM as needed. ROM ROM (read-only memory) chips are nonvolatile storage and control essential system operations. Flash Memory Flash memory does not lose its contents when power is removed. EXPANSION CARDS AND SLOTS Vitalii Petrushenko/Shutterstock SD cards are fingernail-size expansion cards used primarily for laptop computers, tablets, and cell phones. They connect to expansion slots within these devices. Many computers allow users to expand their systems by providing expansion slots on their system boards to accept expansion cards. Examples of expansion cards include graphics cards, network interface cards (NIC; network adapter cards), and wireless network cards. BUS LINES Bus lines, also known as buses, provide data pathways that connect various system components. Bus width is the number of bits that can travel simultaneously. System buses connect CPU and memory. Expansion buses connect CPU and slots. Expansion Buses

Page 127 Three principal expansion bus types: • USB (universal serial bus) can connect from one USB device to another or to a common point (hub) and then onto the system board. • FireWire bus is similar to USB bus but more specialized. • PCI Express (PCIe) bus is widely used; provides a single dedicated path for each connected device. PORTS oleschwander/Shutterstock Ports are connecting sockets on the outside of the system unit. Standard Ports Four standard ports are • USB (universal serial bus)—one USB port can connect several devices to system unit USB-A PCs; USB-B peripherals; USB-C gaining popularity. • HDMI (high definition multimedia interface)—provides high-definition video and audio. • Thunderbolt—provides high-speed connections to up to seven Thunderbolt devices at once, such as external hard drives and monitors. • Ethernet—high-speed networking port that has become a standard for many of today’s computers.

Specialized Ports Three specialty ports are Mini DisplayPort (MiniDP, mDP) for large monitors, VGA (Video Graphics Adapter) and DVI (Digital Video Interface) for connecting to monitors, and FireWire for high-speed connection to devices such as camcorders and secondary storage. Cables Cables are used to connect external devices to the system unit via ports. POWER SUPPLY Akkraraj kangrang/Shutterstock Power supply units convert AC to DC and power desktops. AC adapters power laptops and tablets and recharge batteries. Some cell phones use wireless charging platforms. ELECTRONIC REPRESENTATION Human voices create analog (continuous) signals; computers only recognize digital electronic signals. Numeric Representation Data and instructions can be represented electronically with a two-state or binary system of numbers (0 and 1). Each 0 or 1 is called a bit. A byte consists of 8 bits. Hexadecimal system (hex) uses 16 digits to represent binary numbers. Character Encoding Character encoding standards assign unique sequences of bits to each character. Three standards are • ASCII—American Standard Code for Information Interchange. Historically used for personal computers. • EBCDIC—Extended Binary Coded Decimal Interchange Code. Historically used for mainframe computers.

Page 128 • Unicode—16-bit code, most widely used standard. CAREERS in IT Computer technicians repair and install computer components and systems. Certification in computer repair or an associate’s degree from professional schools is required. Expected salary range is $27,000 to $49,0000. KEY TERMS AC adapter (120) activity tracker (112) all-in-one desktop (109) analog (121) arithmetic-logic unit (ALU) (114) arithmetic operation (114) ASCII (122) binary system (122) BIOS (basic input/output system) (117) bit (122) bus (118) bus line (113, 118) bus width (118) byte (122) cable (120) cache memory (116) cell phone (108) central processing unit (CPU) (114) character encoding standards (122) chip (113) chip carriers (113) clock speed (115) computer technician (123) control unit (114) coprocessor (115) desktop (109) digital (121) DIMM (dual in-line memory module) (116) DVI (Digital Video Interface) port (119)

EBCDIC (122) Ethernet port (119) expansion bus (118) expansion card (117) expansion slot (117) FireWire bus (118) FireWire port (120) flash memory (116) gaming laptops (109) GPU (graphics processing unit) (115) graphics card (117) graphics coprocessor (115) hexadecimal system (hex) (122) High Definition Multimedia Interface (HDMI) port (119) integrated circuit (113) laptop (109) logical operation (114) mainboard (113) memory (116) microprocessor (114) Mini DisplayPort (MiniDP, mDP) port (119) mini notebook (109) mini tablets (109) motherboard (113) multicore processor (115) network adapter card (117) network interface card (NIC) (117) parallel processing (115) PCI Express (PCIe) (118) peripheral (119) personal computer (108) port (119) power supply unit (120) processor (114) random-access memory (RAM) (116) read-only memory (ROM) (116) SD card (117) semiconductor (113) silicon chip (113) slot (113) smartphone (108)

Page 129 smartwatch (112) socket (113) system board (113) system bus (118) system chassis (108) system unit (108) tablet (108) tablet computer (108) Thunderbolt port (119) tower computer (109) tower unit (109) two-in-one laptops (109) ultrabooks (109) ultraportables (109) Unicode (122) universal serial bus (USB) (118) universal serial bus (USB) port (119) Universal serial bus - A (USB-A) (119) Universal serial bus - B (USB-B) (119) Universal serial bus - C (USB-C) (119) VGA (Video Graphics Adapter) port (119) virtual memory (116) wearable computer (112) wearable device (112) wireless charging platform (120) wireless network card (118) word (115) MULTIPLE CHOICE Circle the correct answer. 1. This container houses most of the electrical components for a computer system. a. chip carrier b. system board c. system unit d. Unicode 2. The most popular personal computer. a. all-in-one

b. desktop c. cell phone d. ultrabook 3. The mainboard or motherboard is also known as the: a. computer b. board processor c. mobile system d. system board 4. How many bytes can a 32-bit-word computer access at one time? a. 1 b. 4 c. 8 d. 16 5. In a personal computer system, the central processing unit is typically contained on a single: a. bus b. chip c. module d. RAM 6. This type of memory divides large programs into parts and stores the parts on a secondary storage device. a. direct b. expanded c. random-access d. virtual 7. Also known as NIC, this adapter card is used to connect a computer to a(n): a. AIA b. expansion c. graphics d. network 8. This provides a pathway to connect parts of the CPU to each other. a. bus b. cable c. wired d. wireless 9. The specialized port that is typically used to connect large monitors. a. HDMI b. Ethernet c. MiniDP

__1. __2. __3. __4. __5. __6. __7. __8. __9. __10. 1. 2. 3. Page 130 d. Thunderbolt 10. Computers can only recognize this type of electronic signal. a. analog b. bus c. digital d. maximum MATCHING Match each numbered item with the most closely related lettered item. Write your answers in the spaces provided. a. cache b. flash c. multicore d. NIC e. port f. random- access g. slots h. sockets i. system j. USB A type of multiprocessor chip that provides two or more separate and independent CPUs. A type of memory that is volatile or loses its contents when power is turned off. System board component that provides a connection point for specialized cards or circuit boards. Provide connection points for chips. A type of memory that improves processing by acting as a temporary high-speed holding area between the memory and the CPU. A type of memory that provides a combination of features of RAM and ROM. Another name for a network adapter card. This bus connects the CPU to memory on the system board. This port can be used to connect many USB devices to the system. A socket for external devices to connect to the system unit. OPEN-ENDED On a separate sheet of paper, respond to each question or statement. Describe the five most common types of personal computers. Describe system boards, including sockets, chips, chip carriers, slots, and bus lines. Discuss microprocessor components, chips, and specialty processors.

4. 5. 6. 7. 8. 9. Page 131 Define computer memory, including RAM, ROM, and flash memory. Define SD cards, expansion slots, cards (including graphics cards), network interface cards, wireless network cards, and SD cards. Describe bus lines, bus width, system bus, and expansion bus. Define ports, including standard and specialized ports. Give examples of each. Describe power supply, including power supply units and AC adapters. Discuss electronic data and instructions. DISCUSSION Respond to each of the following questions. Making IT Work for You: Gaming Review the Making IT Work for You: Gaming on pages 110 and 111 and then respond to the following: (a) What type of gaming system do you think you would most enjoy: mobile, console, or PC? Why? (b) Do you own any specialized gaming hardware? If you do, describe the equipment. If you do not, do you have any interest in game playing? Why or why not? (c) Look online to learn the differences between the Microsoft, Sony, and Nintendo consoles. Summarize the differences between the consoles. If you were to purchase a console system, which one would you buy? Defend your choice. Privacy: CRYPTOPROCESSORS Did you know that some systems have specialty processors that automatically encrypt data before storing? Review the Privacy box on page 115, and respond to the following: (a) Who do you think would need a cryptoprocessor? Be specific. (b) Do you think these processors would be worthwhile for you to protect your privacy? Why or why not? (c) Are there any reasons why you might not want all your data encrypted? Explain. (d) Do you think that all computer systems should be required to have cryptoprocessors? Defend your position. Ethics: JOB LOSS AND WORKING CONDITIONS Many computer-related products are produced in other countries, where pay and working conditions are reported to be well below acceptable standards. Review the Ethics box on page 108, and then respond to the following: (a) What do you think about products produced in other countries like China? What are the advantages and disadvantages to consumers? Be specific. (b) What are the ethical issues? Be specific,

and defend your list of issues. (c) Would you be willing to pay more for a computer produced entirely in the United States? More specifically, would you be willing to pay three times as much for a cell phone? Why or why not? (d) Do you think consumers have an ethical responsibility to know how goods are produced? More specifically, would your purchase decisions be affected by knowledge about the working conditions of those who make the product? Why or why not? Environment: RECYCLING COMPUTER HARDWARE Have you ever wondered what you should do with your old computers, monitors, and mobile devices? Review the Environment box on page 114, and then respond to the following: (a) What do you typically do with your used or broken computers and mobile devices? (b) What are three alternatives to throwing these devices in the trash? (c) Using a search engine, find one nonprofit organization near you that will accept used computers. List the name and URL. (d) Visit the waste management or recycling page of your local government’s website. If it does not have a website, contact it. What is its recommended procedure for discarding your computers and other electronic devices? Design Elements: Concept Check icons: Dizzle52/Getty Images; Making IT Work for You: cifotart/Shutterstock