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 When gaining attention and establishing common ground, ask questions of the class such as, “How many of you have ever used USB or FireWire devices?” or “Who has used digital camera or a webcam?” For a WIIFM statement, say to the class, “Imagine someone calling you up and saying everything was working fine on their system until they plugged in a digital camera. Then their keyboard stopped working. They plugged the camera into another computer and everything worked fine. They plugged it back into their computer and the mouse stopped working this time. Why could this happen? In this lesson we’ll learn about this, and more.”

Supporting Common I/O Ports 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 today Other 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 USB 1.1 To get Hi-Speed Speed is total speed of bus 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 Beware of sleeping 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 USB IEEE 1394 FireWire 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 devices supported Max cable length can be up to 4.5 meters

General Port Issues Basic checks If port bad 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

Common I/O Devices

Keyboards Primary method of input USB keyboards Make sure USB keyboard support option enabled in CMOS Some settings available in Keyboard applet

Cleaning the Keyboard Clean the top with cloth dampened with water Can use isopropyl alcohol for 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 Common problem with ball mice 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 Optical mouse Remove dirt from roller Optical mouse Rarely need cleaning Clean optics when necessary

Scanners Enable you to make digital copies of Flatbed scanners 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 Connection 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 to remove card and plug into reader

Digital Cameras Quality measured in megapixels Zoom Form factor 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 to 1.3 million pixels 1.3 megapixels best quality achievable with broadband connection Frame rate How many pictures per second 30 frames per second considered best

Web Cameras Microphones Configuring webcams 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 Many cameras now have the ability to track you when you move, to keep your face in the picture. This interesting technology recognizes a human face and rotates its position to keep your face in the picture. Some companies even add funny extras, such as this webcam program’s animated character, which mirrors your movements as you conference with friends or co-workers.

Specialty I/O Devices

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