f 1 This chapter covers the following subjects: II Understanding liD Ports-This section describes the types of 110 ports used to send information to and from the processor and memory. II Understanding Input Devices-This section describes the important characteristics of keyboards, mice, biometric readers, and other input devices. II Understanding Display Types-This section describes output devices such as CRTs, LCDs, and data projectors. II Understanding Video Connector Types-This section talks about com­ mon video connectors such as VGA, DVI, and HDMI. II Printing Fundamentals-This section describes the basics of laser, inkjet, impact, and thermal printers. .. Understanding Multimedia Devices-This section covers the basics of multimedia devices such as webcams, digital cameras, lV:1IDI ports, micro­ phones, sound cards, and video capture cards. CHAPTER 3 1/0 Ports and Devices Input/output (lIO) devices enable us to control the computer and display infor­ mation in a variety of ways. There are a plethora of ports that connect these de­ vices to the computer, for example, the well-known USB port. To fully understand how to install, configure, and troubleshoot input, output, and multi­ media devices, you need to know the ports like the back of your hand. In this chapter you learn about serial, parallel, SCSI, USB, sound, and FireWire ports and their corresponding devices; the goal is to make you proficient with the var­ ious interfaces you see in the IT field. Understanding 1/0 Ports The word "port" is used often in the computer industry, and has many different meanings depending on what technology is being referred to. In this section, we detail input/output (lIO) ports. VO ports allow for connections to hardware. This hardware could be internal or external. The ports are associated with cop­ per circuits and memory ranges that allow the communication of data between the CPU, RAM, and the ports themselves. Common VO ports include USB and FireWire. In this section, we also discuss SCSI, audio connections, MIDI, and RG-6 coaxial ports. Although the most important VO port on recent systems is the USB port, you might also encounter other ports, including legacy ports such as serial and parallel, which we speak to in this section as well. USB Universal Serial Bus (USB) ports have largely replaced PS/2 (mini-DIN) mouse and keyboard,.serial (COM), and parallel (LPT) ports on recent systems. Most recent desktop systems have at least four USB ports, and many systems support as many as eight or more front- and rear-mounted USB ports. Figure 3-1 shows the rear panel of a typical ATX system, including USB and other port types dis­ cussed in this chapter. Computer Structure and Logic Figure 3-1 A typical An< motherboard's 1/0 ports, complete with legacy (serial, parallel, PS/2 mouse, and keyboard), four USB, one IEEE 1394, two Ethernet, and audio ports. 1. PS/2 mouse port 6. SPDIF coaxial digital audio port 2. PS/2 keyboard port 7. Ethernet ports 3. Parallel port 8. USB ports 4. Serial port 9. 1/B-inch mini-jack audio ports 5. IEEE 1394a port 10. SPDIF optical digital audio port The following sections describe USB port types and how to add more USB ports. USB Port Types, Speeds, and Technical Details There are three standards types of USB ports you need to know: • USB 1.1 • USB 2.0 (also called Hi-Speed USB) • USB 3.0 (also called SuperSpeed USB) The standards use the same cable and COlmector types, which are shown in Figure 3-2. USB cables use two types of connectors: Series A (also called Type A) and Series B (also called Type B). Series A connectors are used on USB root hubs (the USB ports in the computer) and USB external hubs to support USB devices. Series B connec­ tors are used for devices that employ a removable USB cable, such as a USB printer or a generic (external) hub. Generally, you need a Series A-to-Series B cable to at­ tach most devices to a USB root or external hub. Cables that are Series A-to-Series A or Series B-to-Series B are used to extend standard cables, and can cause prob­ lems if the combined length of the cables exceeds recommended distances. Adapters are available to convert Series B cables into Mini-B cables, wbich support the Mini­ B port desigu used on many recent USB devices. Chapter 3: 1/0 Ports and Devices 63 Figure 3-2 USB plugs and sockets. USB type A plug USB type A socket USB type B plug USB type B socket USB Mini-A socket @) USB Mini-B socket 19~ USB Mini-AB socket (g;:n USB Micro-A plug GIiiii, )J USB Micro-B plug [I ,""",I[ USB Mini-A plug USB Mini-B plug USB Micro-B socket ~ USB Micro-AB socket IiLJiii:i'jj USB 1.1 ports run at a top speed (full-speed USB) of 12 megabits per second (Mbps), low-speed USB devices such as a mouse or a keyboard run at I.5Mbps, and USB 2.0 (Hi-Speed USB) ports run at a top speed of 480Mbps. USB 2.0 ports are backward-compatible with USB 1.1 devices and speeds, and manage multiple USB 1.1 devices better than a USB 1.1 port does. USB 3.0 ports run at a top speed of 4,800Mbps. 1 I 64 Computer Structure and Logic USB packaging and device markings frequently use the official logos shown in Fig­ ure 3-3 to distinguish the different versions of USB in common use. Note that the industry is shifting from using the term "USB 2.0" to "Hi-Speed USB." Figure 3-3 The USB logo (left) is used for USB 1.1-compatible devices, whereas the Hi-Speed USB logo (right) is used for USB 2.0--compatible devices. Devices bearing these logos have been certified by the USB Implementers Forum, Inc. With either version of USB, a single USB port on an add-on card or motherboard is desigued to handle up to 127 devices through the use of multipart hubs and daisy­ chaining hubs. Starting with Windows 98, USB devices are Plug and Play (PnP) de­ vices that are hot swappable (can be connected and disconnected without turning off the system). The USB ports (each group of two ports is connected to a root hub) in the computer use a single IRQ and a single I/O port address, regardless of the number of physical USB ports or devices attached to those ports. IRQ Numbers and I/O Addresses An IRQ is an Interrupt ReQuest, the act of a device interrupting the CPU in order to gain its atteution in an effort to send data. This is done by way of an interrupt input line (an acmal circuit). The devices, or ports and their associated controlling chips, are assigued IRQ numbers which help the CPU and interrupt controller to differen­ tiate between devices. For example, the keyboard controller chip is always assigned IRQ 1. A PS/2 mouse is always assigued IRQ 12. The standard IRQ numbers range between 0 and 15. Some are reserved for fumre use by the owner of the computer; this helps with expansion and adding devices to the system. I/O port addresses are ranges of circuits that a device uses to acmally send the data af­ ter they have gained the CPU's attention. These are shown in hexadecimal because they are considered to be memory ranges. For example, the keyboard uses the I/O port address 60. This is known as the base address, or the first in the I/O range. The entire range for the keyboard is 60-6F, a total of 16 values (a 16-bit range). Another example would be the primary IDE controller; this uses the range IFO-IF7, a total of 8 values (an 8-bit range). Because today's operating systems automatically configure these settings for devices, it is rare that you need to troubleshoot device conflicts as­ sociated with IRQs and I/O addresses. J ! I 1 ---------~--~ --- -~ Chapter 3: I/O Ports and Devices 65 The maximum length for a cable attached to 12Mbps or 480Mbps USB devices is five meters, whereas the maximum length for low-speed (1.SMbps) devices such as mice and keyboards is three meters. When a USB root hub is enabled in a computer running Wmdows, two devices are visible in the WIndows Device Manager: a USB root hub and a PCI-to-USB universal host conttoller (USB 1.1) or advanced host conttoller (USB 2.0), which uses the single IRQ and va port address required by USB hardware. If an external USB hub is attached to the computer, a generic hub also is listed in the WIndows Device Manager (see Figure 3-4). A root hub supports two USB ports. In Figure 3-4, there are two root hubs listed, indicating that the sys­ tem has four USB ports. You can access the Device Manager by clicking Start, right-clicking Computer (or My Computer in older WIndows operating systems), and selecting Manage. The Computer Management window opens, and the Device Manager is located there. You can also access Device Manager from the Control Panel. Figure 3·4 The USB section of the Windows XP Device Manager on a typical system. Note the fork-shaped USB logo next to the category and each device. 1. USB category 2. Generic (external) USB hub 3. Device-specific USB support 4. USB root hubs 5.