Peripherals and Custom Computing
- Input/Output, Input Devices, and Peripherals
- Custom PC Configurations
This chapter is from the book
This chapter is from the book
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 Peripherals
To 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 Ports
I/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.
USB
USB 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 Version |
Name |
Data Transfer Rate |
USB 1.0 |
Low-Speed |
1.5 Mb/s |
USB 1.1 |
Full-Speed |
12 Mb/s |
USB 2.0 |
High-Speed |
480 Mb/s |
USB 3.0 |
SuperSpeed |
5.0 Gb/s |
USB 3.1 |
SuperSpeed+ |
10.0 Gb/s |
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.
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FIGURE 13.1 USB 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:
- Device Manager: Within Device Manager, click Universal Serial Bus Controllers to expand it. The root hub and controllers are listed within. Individual devices will be listed under such categories as Human Interface Devices.
- System Information: Open System Information by opening the Run prompt and typing msinfo32. Expand Components, and then select USB.
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:
- Verify that USB is enabled in the BIOS/UEFI: It is possible to enable/disable USB within the BIOS. Keep this in mind when troubleshooting USB devices that are not functioning whatsoever. The user might have inadvertently set this to disabled or perhaps the computer was shipped in that state.
- Make sure the computer is running the correct version of USB: For example, if the computer is USB 3.0-compliant from a hardware standpoint, make sure it is running USB 3.0 on the software side. Some versions of Windows need to be updated to communicate at the latest USB speeds. This update makes a huge difference in the speed of data transfer. Sometimes Windows informs the user that an update to USB is available and that the USB devices work faster if this update is completed. In other cases, a USB firmware update for the motherboard is needed.
- Check the version of the USB port: For example, if a device can run at USB 3.0, make sure it isn’t connected to a USB 2.0 (black port), because that will cause the device to run at USB 2.0 speeds. If it is connected to a slower port, be sure to connect it to a USB 3.0 (blue) port.
- Verify connectivity: Make sure the device is plugged in and that it is using the correct cable. Some incompatible USB plugs might look similar to the correct plug and might even connect to a device.
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 1394
The 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
IEEE 1394 Version |
Data Transfer Rate |
Connector Type |
Cable Length Between Devices |
IEEE 1394a |
400 Mb/s |
4-conductor and 6-conductor |
4.5 meters (15 feet) |
IEEE 1394b |
800 Mb/s |
9-conductor |
10 meters (100 meters with Category 5e cable) |
Thunderbolt
Thunderbolt 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
Thunderbolt Version |
Data Transfer Rate |
Connector Type |
PCI Express Version Required |
Version 1 |
10 Gb/s |
DisplayPort |
Version 2.0 |
Version 2 |
20 Gb/s |
DisplayPort |
Version 2.0 |
Version 3 |
40 Gb/s |
USB Type-C |
Version 3.0 |
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/2
The 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.
Bluetooth
Moving 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
Class |
mW |
Range |
Class 1 |
100 mW |
100 meters (328 ft.) |
Class 2 |
2.5 mW |
10 meters (33 ft.) |
Class 3 |
1 mW |
1 meter (3 ft.) |
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 Devices
I/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
Device |
Description |
Types and Connections |
Keyboard |
Used to type text and numbers into a word processor or other application. |
101-key keyboard is standard, USB, PS/2, and wireless connections. |
Mouse |
Used to control the GUI; works in two dimensions. Might have two or more buttons and a scroll wheel to manipulate the OS. The Buttons tab in Mouse Properties is used to change which buttons act as the primary and alternative click buttons. |
Optical mouse, USB, PS/2, and wireless connections. |
Touchpad |
Device used on a laptop to control the cursor on the screen. |
These are often integrated to the laptop but can also be connected externally via USB or Wi-Fi. |
Motion sensor |
Device used with PCs, Macs, and gaming consoles to allow a user to control the computer by swiping, grabbing, pinching, and so on in mid-air. |
Often connected via USB or Wi-Fi, these are controlled with infrared technology. Some devices can also be controlled with voice activation. |
Digital cameras/Camcorders |
Takes still photographs and/or video using an electronic image sensor. Images are displayed on-screen and can be saved to solid-state media such as SD cards and CompactFlash. |
Can be a single device or integrated into smartphones/tablets. Can connect to the PC via USB or Wi-Fi. |
Web cameras (webcam) |
Enables a user to monitor other areas of a home or building, communicate via video telephony, and take still images. |
Can connect to a PC via USB, to a LAN via RJ45, or via Wi-Fi. |
Scanner |
Used to optically scan images and other objects and convert them into digital images to be stored on the computer. |
Can connect via USB, and IEEE 1394, or via Wi-Fi. |
Microphones |
Enables users to record their voices or other sounds to the computer. Common usages are webcasts, podcasts, for voice-overs while screen capturing, and for gaming. |
Can connect to a PC via 1/8-inch (3.5 mm) mini-jack (sound card) or via USB. |
Biometric devices |
Provides access to systems based on a particular physical characteristic of a user. Used for authentication purposes (for example, a fingerprint reader). |
Can be integrated to the PC or can be connected via USB, Wi-Fi, or connected to the network. |
Barcode readers |
Reads barcodes (for example, linear barcodes, 2D barcodes, Post Office barcodes, and such). After physical installation, they need to be programmed to understand these codes. |
Connects to the PC via USB, Wi-Fi, PS/2, or might be integrated into handheld computers and smartphones. |
Smart card reader |
Device that accepts smart cards used for authentication and data storage. |
Can be integrated as a slot (for, example to a laptop). Also available in USB versions. |
Musical Instrument Digital Interface (MIDI) devices |
Enables computers, music keyboards, synthesizers, digital recorders, samplers, and so on to control each other and exchange data. |
Uses a 5-pin DIN Connector. |
Gamepads and joysticks |
Gamepads are game controllers made famous by Nintendo, PlayStation, and Xbox; there are also gamepads for PCs. Joysticks are often used for flight simulator games. |
Connects via USB Type A connections. Older versions used the 15-pin gaming port on a sound card. |
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
Device |
Description |
Types and Connections |
Touchscreen |
A video display that detects the presence of either a finger, stylus, or light pen that enables interaction with the OS. It incorporates a digitizer (the input portion of the device) that converts the tapping on the screen into digital functions. |
Used in tablet PCs, AIO PCs, smartphones, and drawing tablets. |
KVM switch |
Enables a user to control two or more computers from one Keyboard, Video display, and Mouse (KVM). |
Passive: works off computer’s USB power Active: plugs into an AC outlet. |
Smart TV |
Combines the functionality of a television with Internet features and streaming of media. |
Users can interact with the TV by inputting information via keyboard, gamepad, or remote control. |
Set-top box (STB) |
Device used by cable TV and satellite-based TV providers to allow access to digital (and possibly encrypted) television stations. Also used as a hybrid device that combines conventional TV with Internet technologies. |
These often manifest themselves as small computers offering two-way communications over TCP/IP networks. |
Cram Quiz
Answer 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
What is the data transfer rate (speed) of USB 3.0?
A. 12 Mb/s- B. 400 Mb/s
- C. 480 Mb/s
- D. 5 Gb/s
What is the maximum number of USB devices a computer can support?
- A. 4
- B. 63
- C. 127
- D. 255
Which type of USB connector is normally found on a desktop PC or laptop?
- A. Type A
- B. Type B
- C. Type C
- D. Type D
What is the maximum data transfer rate of IEEE 1394a?
- A. 400 Mb/s
- B. 800 Mb/s
- C. 5 Gb/s
- D. 24 Mb/s
You just installed a barcode reader to a laptop. What should you do next?
- A. Adjust the light wavelength.
- B. Test the reader by reading barcodes.
- C. Program the reader to recognize codes.
- D. Point the barcode reader at someone.
What does a KVM do?
- A. Connects a computer to Bluetooth-enabled devices
- B. Allows multiple users to share a single computer
- C. Networks multiple computers together
- D. Connects multiple computers to save resources
You are installing a wireless keyboard to a PC. What does the PC require?
- A. Bluetooth dongle
- B. Thunderbolt connection
- C. Ethernet connection
- D. IEEE 1394
A user calls you with a complaint that none of his USB devices are working. What is the most probable cause?
- A. The USB 3.0 controller has failed.
- B. The root hub is not configured.
- C. The USB is disabled in the BIOS.
- D. The USB is disabled in Windows.
You plug a USB device into the front panel port of a PC but nothing happens. What is the most likely cause?
- A. The front panel connectors are not plugged into the motherboard.
- B. You plugged a USB 3.0 device into a USB 2.0 port.
- C. You need to reboot the computer.
- D. You plugged a USB 2.0 device into a USB 3.0 port.
Which of the following has a data transfer rate of 40 Gb/s and uses a USB Type-C connector?
- A. USB 3.1
- B. Thunderbolt version 3
- C. Bluetooth version 3
- D. Thunderbolt version 2
Which of the following are considered both input and output devices?
- A. Keyboard, mouse, touchpad
- B. Smart card reader, motion sensor, biometric device
- C. Printer, speakers
- D. Smart TV, touchscreen, KVM, STB
Cram Quiz Answers
220-901 Answers
- D. 5 Gb/s is the data rate for USB 3.0; 12 Mb/s is the data rate for USB version 1.1; and 400 Mb/s is the data rate of IEEE 1394a (FireWire 400). USB 2.0 has a maximum data transfer rate of 480 Mb/s.
- C. USB can support up to 127 devices on one computer. However, USB hubs will be necessary to go beyond the number of USB ports (usually 4 or 6) commonly found on a system. FireWire supports up to 63 devices.
- A. Type A connectors are almost always included on desktop PCs and laptops.
- A. IEEE 1394a (FireWire 400) specifies a maximum data transfer rate of 400 Mb/s. IEEE 1394b (FireWire 800) specifies 800 Mb/s. USB 3.0 runs at 5 Gb/s. Bluetooth version 3 runs at 24 Mb/s.
- C. After installing the device as well as the driver for the device, program the reader to recognize the codes.
- D. A KVM connects multiple computers to a single keyboard, mouse, and monitor. This way, fewer resources in the way of peripherals (input/output devices) are necessary to use the computers.
- A. Wireless keyboards and mice often use Bluetooth to transmit to a PC or laptop. The computer must either have a built-in Bluetooth antenna or a Bluetooth dongle connected to a USB port for the keyboard to function. These types of devices do not connect to Thunderbolt, Ethernet, or IEEE 1394 ports.
- C. If none of the USB devices are working, chances are that USB has been disabled in the BIOS. This might be company policy so that users can’t access USB drives or boot the computer to a USB drive. If the USB 3.0 controller fails, the USB 2.0 controller should still be functioning for other ports. The USB root hub requires no configuring; it is auto-configured by Windows. Although it might be possible to disable one USB device at a time in Windows, it will be uncommon. Disabling all the devices in Windows is rare.
- A. Most likely, the front panel connectors are not plugged into the motherboard. A USB 3.0 device will work fine in a USB 2.0 port but at the lower speed. A USB 2.0 device will work at USB 2.0 speed when plugged into a USB 3.0 port. Rebooting is usually not necessary when installing USB devices.
- B. Thunderbolt version 3 has a data transfer rate of 40 Gb/s and uses a USB Type-C connector. Although SuperSpeed+ USB 3.1 can use the newer USB Type-C connector, it has a data transfer rate of 10 Gb/s. Bluetooth version 3 has theoretical speeds up to 24 Mb/s. Thunderbolt version 2 transfers data at 20 Gb/s and uses a DisplayPort (or Mini DisplayPort) connector.
- D. Smart TVs, touchscreens, KVMs, and STBs are considered both input and output devices. Keyboards, mice, touchpads, smart card readers, motion sensors, and biometric devices are considered input devices. Printers and speakers are considered output devices.