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Input/Output. Chapter 16. Overview. In this chapter, you will learn to Explain how to support common input/output ports Identify certain common input/output devices on a PC Describe how certain specialty input/output devices work on a PC. Essentials. CompTIA A+ Essentials.
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Input/Output Chapter 16
Overview • In this chapter, you will learn to • Explain how to support common input/output ports • Identify certain common input/output devices on a PC • Describe how certain specialty input/output devices work on a PC
Essentials CompTIA A+Essentials Supporting Common I/O Ports
Serial Ports • Converts data between serial and parallel devices • RS-232 Standard • Primary standard used for serial devices • Rarely used todayOther standards (such as USB) much quicker • COM ports are serial • 9-pin connector • Used by modems and other devices
Serial Properties • Speed set in bits per second • 75 bps to 128,0000 bps • Size of data chunks sent • 7 or 8 bits • Stop bits • Identify end of chunk • Flow control
USB Ports • Understanding USB • Host controller in chipset: contains root hub
USB Speeds • USB 2.0 • Runs at 480 Mbps (Hi-Speed) • USB 1.1 • 1.5 Mbps (Low-Speed) and 12 Mbps (Full-Speed) • To get Hi-Speed • Hi-Speed device must be plugged into Hi-Speed port with Hi-Speed cable • Speed is total speed of bus • Divided between all the devices • Most systems support both 1.1 and 2.0
USB Hubs and Cables • USB controller supports up to 127 devices • Won’t find 127 USB ports on any computer • Add hubs to add additional ports • Hubs can be powered or unpowered • Cables can’t be longer than 5 meters
USB Configuration • First rule of USB device installation • Always install driver BEFORE installing device • UVCView shows controllers and hubs • Microsoft tool—free download
USB • Device Manager shows all USB devices • Locate USB hub under Universal Serial Bus Controller icon • Has a Power tab to show power properties • Beware of sleeping devices • System tells them to sleep to save power • Sleeping devices no longer appear in Device Manager • Uncheck Allow the computer to turn off this device to save power
FireWire • Similar to USB • Different speeds and different connectors • IEEE 1394 • 1394a runs at 400 Mbps • 1394b runs at 800 Mbps • USB • FireWire
FireWire • Devices can be connected to a hub or daisy-chained • Up to 63 devicessupported • Max cable length can be up to 4.5 meters
General Port Issues • Basic checks • Is the port bad or the device bad? • Plug in known good device to check port • If port bad • Check CMOS—turned off? • Check Device Manager—disabled?
General Port Issues • Check for physical damage • Bent, missing pins • Sometimes possible to reshape pins and plugs
Keyboards • Primary method of input • USB keyboards • Make sure USB keyboard support option enabled in CMOS • Some settings availablein Keyboard applet
Cleaning the Keyboard • Clean the top with cloth dampened with water • Can use isopropyl alcoholfor stubborn dirt
Cleaning the Keyboard • Cleaning under the keys • Start with compressed air • Can sometimes take the layers apart and clean • Keep track of the location of all keys and parts • Allow sheets to dry before reassembling • Careful when removing keys—can break them
Mice • Hot keys do exist to work without mouse • Mouse applet in Control Panel • Slightly different in 2000 and XP • Can adjust buttons and speed of movement
Mice • Two primary technologies • Ball mice—use small round ball • Optical mice—use LEDs or lasers • Common problem with ball mice • They get dirty • Mouse pointer becomes jumpy
Cleaning the Mouse • Remove the ball • Remove dirt from roller • Optical mouse • Rarely need cleaning • Clean optics when necessary
Scanners • Enable you to make digital copies of • Photos • Documents • Drawings • And more • Flatbed scanners • Place document on the glass • Close the lid • Run the software
Scanners • Software used to capture image • Default driver: • TWAIN (Technology Without An Interesting Name) • Common software • Photoshop • Paint Shop Pro • Printer-specific
How to Choose a Scanner • Consider five primary variables: • Resolution: dots per inch (dpi) • Color depth: bits used for color (8, 16, 24, 36, 48) • Grayscale depth: bits for shades of gray (8, 16, more) • Connection: typically USB or FireWire • Scan speed: seconds 72 dpi 300 dpi 1200 dpi
Installing and Scanning Tips • Typically USB or FireWire connections • Install drivers before plugging in • Do the best quality possible first • Then manipulate size and quality for end use • Two resources affect what you can do: • RAM: 8x10 @ 600 dpi is about 93 MB • Processor speed
Installing and Scanning Tips • Keep the glass clean • Dirty glass results in dirty scans • When moving the scanner • Use the locking mechanism for the scanner light assembly
Digital Cameras • Storage media—digital film • Secure Digital (SD) card common • About the size of Wheat Thin • Sizes range from 64 MB to 1 GB • Connection • USB and FireWire common • Allow you to read data from card while in camera • Card readers allow you toremove card and pluginto reader
Digital Cameras • Quality measured in megapixels • 2-megapixel can produce quality 4x6-inch photos • 5-megapixel can produce quality 8x10-inch photos • Zoom • Optical zoom—physically built into the lens • Digital zoom—software provides zoom capabilities • Optical zoom more important when comparing camera quality • Form factor • Larger usually means better quality
Web Cameras • Used for Internet interaction • Biggest issue is image quality • Resolutions between 100,000 to1.3 million pixels • 1.3 megapixels best quality achievable with broadband connection • Frame rate • How many pictures per second • 30 frames per second consideredbest
Web Cameras • Microphones • Some webcams have microphones • Can use your own headset • Configuring webcams • USB connections common • Install drivers first
Web Cameras • Configuring software—common steps • Tell the program you want to use a camera • Tell the program whether you want the camera to turn on automatically when you chat • Configure the image quality • Test the camera
Biometric Devices • Used for authentication • Fingerprints • Retinal scans • Voice recognition
Bar Code Readers • Designed to read standard Universal Product Code (UPC) • Frequently used to track inventory • Includes asset inventory • Also used in point-of-sale systems
Touch Screens • Monitor with sensing device on face • Detects location of touch • Either by finger or stylus • Responds as if it were a mouse click • Touch screens can be seen in • Information kiosks • PDAs • Point-of-sale systems • Tablet PCs