What is the technology used to wire almost all external devices keyboard mouse storage etc to a computer?
Learn about the devices and peripherals we add on to the computer, the ports they connect to, as well as some custom PC configurations you will undoubtedly encounter in the field. Show
This chapter is from the book The computer is built, the OS is installed, and video is configured. Now let’s discuss the devices and peripherals we add on to the computer, the ports they connect to, as well as some custom PC configurations you will undoubtedly encounter in the field. Input/Output, Input Devices, and PeripheralsTo take advantage of a computer, the appropriate input/output devices and peripherals must be connected to the proper input/output (I/O) ports. Keyboards, mice, and multimedia devices can be connected to a variety of ports. This section briefly describes those devices and the ports they connect to. I/O PortsI/O ports enable a user to input information by way of keyboard, mouse, or microphone; plus they enable the output of information to printers, monitors, USB devices, and so on. The CompTIA A+ exams require you to describe USB, IEEE 1394 (FireWire), and Thunderbolt ports, as well as Bluetooth technology. The most common of these by far is USB. USBUSB ports are used by many devices, including keyboards, mice, printers, flash drives, cameras, and much more. The USB port enables data transfer between the device and the computer and usually powers the device as well. The speed of a USB device’s data transfer depends on the version of the USB port, as shown in Table 13.1. TABLE 13.1 Comparison of USB Versions
USB 1.0 and 1.1 are deprecated. If you encounter an older computer that has only these ports, consider installing a USB adapter card that adheres to a higher version of USB. A computer can have a maximum of 127 USB devices. However, most computers are limited to a maximum of a dozen ports or so. To add devices beyond this, a USB hub can be used, but no more than five hubs can be in a series of USB devices. All cables connecting USB devices must comply with their standard’s maximum length. USB version 1.1 cables are limited to 3 meters in length (a little less than 10 feet), and USB version 2.0 cables can be a maximum length of 5 meters (a little more than 16 feet). Maximum recommended USB 3.0/3.1 length is 3 meters. The standard USB cable has four pins: a +5 V pin for power, a positive data pin, a negative data pin, and a ground pin. Most USB connections are half-duplex, meaning that the device can send or receive data but cannot send and receive data simultaneously. There are various plugs used for the different types of USB connections. The most common are Type A and Type B, which are 4-pin connectors, but there are also mini- and micro-connectors, which are 5-pin. Type A connectors are the type you see on the back of a computer or on the side of a laptop. Figure 13.1 displays an illustration of these connectors. Type A and Type B connectors are commonly used for printers and other larger devices. Mini- and micro-connectors are often used for handheld computers, smartphones, mice, digital cameras, portable music players, and cell phones. However, some companies create proprietary cables and connectors for their devices based off of the USB specifications. These devices will not connect properly to Type A, Type B, and mini- or micro-connectors. You can’t put a square peg in a round hole (normally). Sometimes you need to make a connection but the devices and/or cables don’t match up, so you’ll need an adapter—and there are adapters for virtually everything you might want to do. Let’s say you need to make a connection to a USB Type B connector from a USB Type A connector, or you need to connect from USB to RJ45, or you need to connect from a USB to the older PS/2 connector—well, there are adapters for all of those situations and more. Most PC technicians will carry a variety of adapters with them just in case the need arises. Something to think about for your PC toolkit. Historically, a USB device was designed to be a host or a slave. The host is in charge of initiating data transfers (for example, a PC). However, USB version 2.0 introduced on-the-go (OTG), which enables a device to act as both a host and a slave. This is more common in handheld computers and smartphones (devices that connect with either mini- or micro-plugs). USB devices connect to what is known as a root hub, regardless of whether they are USB version 1.1, 2.0, or 3.0 devices. The USB devices, root hub, and host controllers can be viewed from within Windows in a couple ways:
Windows offers a disk-caching component called ReadyBoost. This uses flash-based memory such as USB flash drives and SD cards to cache information for the OS at high speeds. The cache can be as much as 32 GB in size on one device or 256 GB in size if spread across multiple devices. For USB flash drives, this technology works best at USB 3.0 speeds (or higher). When troubleshooting USB devices, keep a few things in mind:
When removing USB devices from a computer, remember to disable them in the Notification Area before disconnecting them. Do this by right-clicking on the Safely Remove Hardware and Eject Media icon and selecting Eject. This will avoid damage to a USB device (for example, corruption to the USB flash drive). If you cannot disable it in the system, power down the computer and then disconnect them. For more information about USB, visit http://www.usb.org. One of the problems with USB is that it suffers from latency. Due to this fact, users who work with audio and video prefer a zero-latency connection, such as IEEE 1394. IEEE 1394The Institute of Electrical and Electronics Engineers (IEEE) is a nonprofit organization that creates standards regarding cables and connectors and other technology related to electricity. One common standard is IEEE 1394, also referred to as FireWire (a deprecated Apple standard replaced by Thunderbolt). It is a port used for devices that demand the low-latency transfer of data in real time, such as music or video devices. Up to 63 devices can be powered by a computer, with no more than 16 devices per chain. Table 13.2 describes some of the IEEE 1394/FireWire versions. TABLE 13.2 Comparison of IEEE 1394/FireWire Versions
ThunderboltThunderbolt is a high-speed hardware interface developed by Intel. As of the writing of this book, this is used primarily by Apple computers. It combines elements of PCI Express and DisplayPort technologies. Versions 1 and 2 use the Mini DisplayPort connector and version 3 uses the USB Type-C connector. Cables used with Thunderbolt should be no more than 3 meters (copper) and 60 meters (optical). Thunderbolt 2 gives you access to the latest 4K monitors. In fact, with the Mac Pro, you can connect up to three 4K displays at once. And because Thunderbolt is based on DisplayPort technology, it provides native support for the Apple Thunderbolt Display and Mini DisplayPort displays. DVI, HDMI, and VGA displays connect through the use of adapters. Thunderbolt can be used to transfer data at high rates to external storage devices or to displays (or both; up to six devices can be daisychained, meaning wired together in sequence). If you look at the ports of the computer and see the thunderbolt icon next to the Mini DisplayPort port, then it is meant to be used for data transfer to peripherals. If you see a display icon, then it can be used with a monitor. While you can physically connect a Thunderbolt device to a Mac with DisplayPort, the device will not work, but if you connect a DisplayPort device to a Mac with Thunderbolt, the device will work. Table 13.3 describes the different versions of Thunderbolt. TABLE 13.3 Comparison of Thunderbolt Versions
If a desktop computer doesn’t come with a Thunderbolt connector, you can add a Thunderbolt adapter card, which can facilitate the use of high-speed, large-capacity storage devices and other technologies. There are also adapters that connect Thunderbolt to USB 3.0 and eSATA. On the video side, there are adapters that allow Thunderbolt to be changed over to DVI or to HDMI. As mentioned before, there are adapters for everything. If you can dream it up, it probably already exists. PS/2The PS/2 connector is used for connecting keyboards and mice to a desktop computer or laptop. The PS/2 port was originally introduced in the late 1980s as part of IBM’s Personal System/2 computer. Keyboards and mice connect via a 6-pin Mini-DIN connector. In the PC 99 color scheme, PS/2 keyboard ports are purple and PS/2 mouse ports are green. Although PS/2 had almost a 20-year run, these connectors are less common on new computers; they were the standard until USB became popular. However, like the older DB15 VGA port, you might see them for backward compatibility. For example, the AV Editor computer’s motherboard has a single PS/2 port. BluetoothMoving on to a wireless option for peripherals: Bluetooth is a short-range, low-speed wireless network primarily designed to operate in peer-to-peer mode (known as ad hoc) between PCs and devices such as printers, projectors, smartphones, mice, keyboards, and so on. It can be used with gaming consoles and by connecting a smartphone to a car’s technology system or to a smart TV. Bluetooth runs in virtually the same 2.4 GHz frequency used by IEEE 802.11b, g, and n wireless networks, but it uses a spread-spectrum frequency-hopping signaling method to help minimize interference. Bluetooth devices connect to each other to form a personal area network (PAN). Some systems and devices include integrated Bluetooth adapters, and others need a Bluetooth module connected to the USB port to enable Bluetooth networking. Bluetooth devices must first be paired before they can be used together. Bluetooth version 1.2 offers a data transfer rate of 1 Mb/s. Version 2 is rated at 3 Mb/s. Version 3 has theoretical speeds of up to 24 Mb/s, but it does so by combining with 802.11 technology. Bluetooth is divided into classes, each of which has a different range. Table 13.4 shows these classes, their ranges, and the amount of power their corresponding antennae use to generate signal. TABLE 13.4 Bluetooth Classes
As you can see, Class 1 generates the most powerful signal and has the largest range. The most common Bluetooth devices are Class 2 devices, with a range of 10 meters. Examples of this include portable printers, headsets, and computer dongles that connect to USB ports and allow the PC to communicate with other Bluetooth-enabled devices. Input, Output, and Hybrid DevicesI/O devices (also called peripherals) can be used solely to input information, to output information, or to act as a hybrid of the two. Let’s start with the types of devices used to input information and the various peripherals a technician might see in the field. The usual suspects include the keyboard, for typing information in Windows or other OS, and the mouse, for manipulating the GUI. These two are known as human interface devices (HID). Some other devices that you might not have worked with yet include touchpads, digital cameras, web cameras, microphones, biometric devices, bar code readers, and MIDI devices. Table 13.5 describes these devices. TABLE 13.5 Description of Various Input Devices and Peripherals
Troubleshooting any of the devices in Table 13.5 is usually quite easy. Make sure that the device is connected properly to the computer (or has a working wireless connection) and verify within the Device Manager that the latest drivers are installed for the device. Then find out if any additional software is necessary for the device to function. Portions of the software might have to be installed to the device and to the OS. Keyboards and mice can be especially troublesome. Keyboard errors are commonly caused by jammed keys and defective cables or cable connectors. A common mouse issue is when the cursor jumps around the screen. This could be due to an incorrect mouse driver or perhaps the mouse is on an uneven or nonreflective surface. Also, you might encounter a mouse that stops working after a computer comes out of sleep mode. Make sure that Windows is updated and that the correct and latest driver is being used for the mouse. Use the associated Control Panel apps to troubleshoot the device. Calibrate the device and/or synchronize the device to the system as necessary. The main output devices you should know for the exams are display devices and speakers (covered in Chapter 12) and printers (to be discussed in Chapter 14). Because they are covered in those chapters, we will not discuss them here. A few of the hybrid devices you will encounter are touchscreens, KVMs, smart TVs, and set-top boxes. Table 13.6 describes those in brief. TABLE 13.6 Description of Hybrid I/O Devices
Cram QuizAnswer these questions. The answers follow the last question. If you cannot answer these questions correctly, consider reading this section again until you can. 220-901 Questions
Cram Quiz Answers220-901 Answers
What is the name for a device that is connected to the computer externally?External hardware components, also called peripheral components, are those items that are often externally connected to the computer to control either input or output functions. These hardware devices are designed to either provide instructions to the software (input) or render results from its execution (output).
What software controls a computer and its peripherals such as its keyboard and mouse?Operating system (OS) – a software that controls and coordinates the computer hardware devices and runs other software and applications on a computer. It is the main part of system software and a computer will not function without it.
What type of devices are external keyboards and optical mouse?Input devices include typewriter-like keyboards; handheld devices such as the mouse, trackball, joystick, trackpad, and special pen with pressure-sensitive pad; microphones, webcams, and digital cameras.
What item is essential for connecting external devices to your computer?USB (Universal Serial Bus) Port
Most desktop computers have several USB ports. These can be used to connect almost any type of device, including mice, keyboards, printers, and digital cameras.
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