Section 4.1: Peripheral Devices

Transcription

1 Section 4.1: Peripheral Devices A peripheral device is a device that connects through an external port to your computer. The following connection types are common: Interface PS/2 Description PS/2 connectors are 6-pin mini-din connectors. Keyboard and mouse are common devices that use PS/2 connections. The correct device must be connected to the correct port; a specific port is used for the keyboard, with a different port for the mouse. Devices can be auto-detected, but must be plugged in when the computer starts up. USB is a serial interface that supports low- and high-speed devices. USB supports almost any kind of peripheral device, including: o Keyboards o Mice o Scanners o Digital cameras o Web cams and camcorders o Microphones o MIDI-enabled devices (such as musical keyboards) o Printers o Storage devices USB USB ports on video cameras are typically used for transferring still images to the computer. USB supports Plug-and-Play and hot swapping (adding and removing devices without rebooting--also known as hot plugging). To install a USB device, you should typically install the software driver before attaching the device. When you plug in the device, it will be automatically detected and configured. Edit the BIOS settings to disable onboard USB ports or configure the USB mode for either version 1.1 or 2.0. All devices connected together share computer resources (IRQs, I/O addresses). Firewire Firewire is a serial interface. Common Firewire devices include digital video cameras and recorders, hard drives, and network adapters. Firewire ports on video cameras are typically used for transferring digital video. 1

2 Firewire supports Plug-and-Play and hot-swapping Serial Serial devices transmit data one bit at a time on a single cable. Serial devices use COM ports for system resources. Remember that COM ports 1 and 3, and ports 2 and 4 are shared. If you install a serial device on both COM 1 and COM 3, the devices might cause a resource sharing problem. The most common serial device is a modem. Some specialized printers might also use a serial interface. Many newer computers no longer include a serial port. To add serial ports to a computer, install an adapter card. Parallel Parallel devices transmit multiple bits at a time over multiple wires. Parallel devices use LPT ports for resources. Common parallel devices include printers and scanners. Parallel communication uses one of the following standards (or modes): o Standard Parallel Port (SPP) o Enhanced Parallel Port (EPP) o Extended Capabilities Port (ECP) Both EPP and ECP support bi-directional communication. ECP supports DMA. Edit the CMOS settings to configure the parallel modes supported. PC Card (PCMCIA) PC Card expansion slots are used in laptops and portable devices. PC Card slots can be used by devices like modems, network cards for wired or wireless networks, CD-ROMs, sound cards, SCSI host adapters, IEEE 1394 controllers, USB controllers, and others. PCI Express (ExpressCard) PCI Express (ExpressCard) is replacing PC Card for laptop expansion devices. ExpressCard slots connect directly to the PCIe or USB bus. Cards use either PCI Express or USB 2.0 standards (the slot supports both). ExpressCards can be used for all types of devices, similar to PCMCIA. An ExpressCard can even be used for a graphics card to attach an external monitor. Many newer laptops have ExpressCard slots but not PCMCIA slots. Some laptops have both, while some have neither (assuming that all external devices will connect through the USB 2

3 ports). Many of these ports and interfaces are included as part of the motherboard faceplate connectors. To add support for additional ports, do one of the following: If the motherboard includes header connections for the ports, connect the cables and ports to the system case or an expansion slot. Add an expansion card to provide the necessary ports. Consider the following troubleshooting techniques specific to each device: Device Considerations Check the following when troubleshooting input devices: Input devices Make sure the device is plugged in securely. For PS/2 keyboards and mice, make sure they are using the correct port. Having the mouse and keyboard switched can result in a Keyboard not found error during boot. Clean the mouse roller ball and the keyboard. For stuck or malfunctioning keyboard keys, you might be able to pop the key off and clean the contact underneath. Be aware that replacing the keyboard might be cheaper than spending a lot of time cleaning it. Make sure that nothing is on the keyboard as the system boots. If a key is pressed during the bootup process, a 301 (keyboard) error can result. If this happens, you will more than likely have to reboot. For wireless devices, change the batteries if necessary. If advanced features are not available for the device, update or install the correct device driver. To troubleshoot USB and Firewire devices, consider the following: USB/Firewire Install the driver before plugging in the device. Overloading the power resources of the USB bus can cause devices to not have sufficient power to work properly. Make sure that you are not exceeding 500 MA of power through the USB bus. Different versions of USB devices have different capabilities. There are two main versions of USB devices: 1.1 and 2.0. Most 2.0 controllers are backwards-compatible with 1.1 devices, but 1.1 controllers rarely work with 2.0 devices. Backwards plug insertion is easy to do with Firewire. This can cause your wires to start smoking and can possibly ruin the device. The cable might be too long for the current setup. Remember that shorter cable lengths are best; you should try not to use cables that are longer than 3-4 feet. Verify BIOS settings for onboard USB and Firewire. Make sure 3

4 onboard ports are enabled, and that the correct USB version is enabled. Common interfaces used for connecting input devices include: 6-pin mini-din (PS/2 connector) for keyboard and mouse USB for keyboard, mouse, and other devices Infrared and wireless connections for keyboards, mouse, and other devices DB-9 (serial) connector for specialized input devices The following table lists several considerations for selecting input devices. Device Type Considerations Keyboard Keyboards typically connect through a PS/2 or USB port. Many keyboards include special function keys that simplify playing music or browsing the Web. Some keyboards include a built-in USB port that can be used to connect other peripheral devices. A mouse typically connects through a PS/2 or USB port. A wireless mouse typically transmits to a receiving station attached through a USB port. Mouse Mechanical mice use a roller ball to detect motion. The roller ball must be cleaned periodically to ensure proper functionality. Optical mice use light rays to detect motion. Optical mice require less maintenance than mechanical mice. Motion-based mice can accurately detect mouse movement while in the air. This particular device can attach to a user's head and moves the cursor when the head moves. You can select mice with multiple additional buttons or a scroll wheel to add functionality. A trackball is a pointing device that is like an upside-down mechanical mouse where the user manipulates the pointer by rolling the ball. A touchscreen is a special monitor that allows input by tapping or writing with a stylus or fingers. Touchscreens are used in kiosks and portable devices such as PDAs and Tablet PCs. There are three basic types of touchscreens: Touchscreen A capacitive screen uses a thin electrically charged layer placed over the monitor screen. When touched, the charge moves from the capacitive surface to the touching object. The screen location of the touch is calculated and sent to the computer. This method blocks some of the light emanating from the monitor. A resistive screen uses a glass panel covered with two metallic 4

5 layers (one conductive and the other resistive) separated by a very narrow gap and mounted over the monitor screen. A protective layer is applied to the touch surface. When the screen is touched, the two metallic layers make contact and that location is calculated. This type of touchscreen also blocks some of the monitor's light emanation. A surface acoustic wave screen places tiny matching transducers across the screen surface from each other (one to send and the other to receive). When an object touches the screen surface, the signal is interrupted and that location is then calculated. This type of touchscreen does not visually impair the monitor. Digitizer A digitizer captures some type of analog signal and converts it to digital data. Digitizer pads (also called graphics tablets) can be connected to PC systems to allow the user to write on the pad with a stylus and have the input captured as digital data. These devices are frequently used by graphic artists to capture hand-drawn images as digital input for the PC. Game pad Game pads can be connected to PC systems to provide additional functions needed to play games. Using a game pad eliminates the need to use the keyboard and mouse to control game movements. Scanner Scanners are used to scan hard-copy images and documents and convert them into digital input for the PC. For example, photos can be scanned into image files while documents can be scanned into editable word-processor documents using optical character recognition (OCR). A barcode reader is a device that can scan barcodes. Barcode reader Barcodes are most commonly used in retail environments at checkout stands. Shipping companies, hospitals, and other organizations use barcodes to track or inventory objects. Most bar code readers use a laser to scan the barcode, although some do use cameras or optical scanners. Older readers used a serial interface, while newer readers use USB or PS/2. Barcode readers include software that interprets the meaning of the barcode. KVM switch A KVM (keyboard, video, mouse) switch allows you to connect multiple PCs to a single set of input/output devices. KVM switches have multiple input groups, with each group accepting keyboard, video, and mouse connections from a single computer. A single output group connects to the shared input/output devices. Buttons on the KVM switch or keyboard shortcut combinations allow you to toggle the input/output devices between computers. KVM switches are typically used in a data center where you manage multiple computers from a single central console. 5

6 Local KVM switches must be within about 5 meters of the connected computers. Networked or remote KVM switches use special hardware devices that send keyboard, mouse, and video content through a network connection. Lecture Focus Questions: What is the difference in the way that serial devices transmit data and parallel devices transmit data? Why might you have a resource sharing problem if you install a serial device on both COM 2 and COM 4? What type of ports are common parallel devices such as printers and scanners connected to? What types of peripheral devices does USB support? How can you verify that a device is compatible with the version of Windows on the system? What is different about installing a USB device driver and installing drivers for other device types? Section 4.2: Serial, Parallel, and PS/2 The following table describes the serial, parallel, and PS/2 interfaces for connecting devices. Interface Description You should know the following facts about serial devices: Serial Data is transmitted one bit at a time. Data can be transferred greater distances using serial communication techniques. The maximum length for an RS-232 serial cable is 50 feet. Serial devices use COM ports for system resources. Remember that COM ports 1 and 3, and ports 2 and 4 are shared. If you install a serial device on both COM 1 and COM 3, the devices will experience a resource sharing conflict. Serial ports on the back of a computer are always male connectors. The most common serial device is a modem. Some older printers might also use a serial interface. Many newer computers no longer include a serial port. To add serial ports to a computer, install an adapter card. 6

7 You should know the following facts about parallel devices: Data is transmitted 8 bits (one byte) at a time (using 8 data transmission wires). Parallel devices use LPT ports for resources. Parallel ports on the back of a computer are always female connectors. The most common parallel devices are printers. Data is transferred faster than with serial communications. There are two common types of parallel cables: Parallel Devices An IBM Printer cable is a unidirectional cable with a 25-pin male DB25 connector at one end and a 36-conductor male Centronics connector at the other end. IEEE 1284 is a newer, bi-directional cable more commonly used. Connectors used are similar to the IBM printer cable, but with different connector genders possible. o The maximum specified length is 10 meters (approx. 30 feet). o Data can be transferred at up to 2 MB/s. Parallel communication uses one of the following standards: Standard Parallel Port (SPP) o Original parallel port standard. o Transfers data in a single direction (away from the computer). o 50 to 150 kilobytes per second. o Cables should be less than 10 feet in length. Enhanced Parallel Port (EPP) o 500 kilobytes per second to 2 megabytes per second. o Supports bi-directional communications. o Used by non-printing devices. Extended Capabilities Port (ECP) o Requires an ECP chip on the system board. o This standard is especially good for achieving high data rates for input rather than output. o Supports bi-directional communications. o Supports DMA. Most motherboards include a parallel port that supports all three modes. Edit the BIOS to configure the parallel port mode. PS/2 IBM came out with a line of computers in 1994 called PS/2. This computer line introduced a small, fixed-pin adapter for both mice and keyboards. While the PS/2 computer line itself eventually was discontinued, the PS/2 connectors continued to be used extensively for some time. In recent years, PS/2 devices have been replaced by devices that use a USB interface. PS/2 devices (specifically keyboards and mice) must be plugged into your computer before it is turned on in order for the computer to recognize them. 7

8 The following table shows common connectors for serial, parallel, and PS/2 components. Connector Description You should know the following facts about serial cables and connectors: Serial Connector The maximum length for an RS-232 serial cable is 50 feet. Serial ports on the back of a computer are always male connectors. The original serial standard called for a 25-pin connector. However, because only 9 pins of the connector were used, manufacturers moved to a 9-pin connector. There are two common types of parallel cables: Parallel Connectors An IBM Printer cable is a unidirectional cable with a 25-pin male DB-25 connector at one end (top graphic on the left) and a 36-conductor male Centronics connector at the other end (bottom graphic on the left). IEEE 1284 is a newer, bi-directional cable more commonly used. Connectors used are similar to the IBM printer cable, but with different connector genders possible. o The maximum specified length is 10 meters (approx. 30 feet). o Data can be transferred at up to 2 MB/s. You should know the following facts about parallel connectors: Parallel ports on the back of a computer are always female connectors. The IEEE 1284 specifies a daisy chaining standard that allows up to eight devices to be connected to a single parallel port. PS/2 Connectors PS/2 connectors are 6-pin mini-din connectors. The connector's sleeve has a notch to ensure proper alignment when inserted into the port and to prevent the pins in the connector from being 8

9 bent. Both the keyboard and the mouse use the same type of connector, so it's important to connect the correct device to the corresponding port. Most motherboard faceplates include a small graphic indicating keyboard or mouse. The keyboard connector is typically towards the outside of the motherboard faceplate. The PC99 standard uses purple for the keyboard and green for the mouse. An older color scheme uses orange for the keyboard and purple for the mouse. Lecture Focus Questions: What is the difference between serial and parallel communications? Generally speaking, which form of communication (serial or parallel) will provide communication over longer distances without amplification? What is the relationship between the serial port and the COM ports? Between the parallel port and LPT ports? What is the difference between SPP and EPP standards? What are three ways you can tell the difference between a keyboard and mouse PS/2 port? How do you configure a computer to use EPP? Section 4.3: USB You should know the following facts about USB: USB is a serial interface that supports low- and high-speed devices. USB supports almost any kind of peripheral device, including keyboards, mice, scanners, digital cameras, printers, and storage devices. USB supports Plug-and-Play and hot swapping (adding and removing devices without rebooting--also known as hot plugging). USB allows 127 devices to be connected to a single computer (directly to the host or by hubs). All devices connected together share computer resources (IRQs, I/O addresses). The computer's BIOS must support USB and have USB enabled. USB comes in multiple versions that perform at different rates, for various devices, as listed in the table below. 9

10 Version Speed Data Transfer Rate (megabits per second) Maximum Cable Length (meters) 1.0/ Mbps 3 m 12 Mbps 5 m 2.0 Lowspeed Fullspeed Highspeed 480 Mbps 5 m 3.0 Super- Speed Up to 5 Gbps 3 m Version 2.0 is backwards compatible with version 1.1 devices. Likewise, Version 3.0 is backwards compatible with version 2.0 devices. Most motherboards allow you to enable/disable USB support in the BIOS, or configure the USB version that will be used. The table below describes the types of USB connectors. Connector Description A Connector Rectangular connector that generally plugs directly into the computer or a hub. B Connector D-shaped connector that plugs into a hub, printer, or other peripheral device to connect the device to the computer. Most USB cables have an A connector on one end (to connect to the computer or hub) and a B connector on the other end (to connect to the device) Mini Connector (4 pin) Small square connector designed to plug in to devices with mini plugs such as a digital camera. Most USB cables with a mini 10

11 connector have an A connector on the other end to connect to the computer Mini Connector (5 pin) Small connector designed to plug in to devices with mini plugs such as a digital camera. Micro Connector Micro USB connectors are designed for smart phones and tablet devices. As such, micro USB connectors are quickly replacing mini USB connectors. Micro USB connectors are approximately half the thickness of Mini USB connectors, making them more appropriate for smaller devices. You can connect a USB device to a computer in two ways: Directly to a USB port on a computer (it is common for a computer to have two USB ports). In addition, many motherboards include additional USB headers that can be used to attach additional USB ports. To an external USB hub. Hubs can be chained together to provide additional ports. A hub has a single B connector to connect to the computer, and multiple A connectors for attaching devices. USB devices can be classified according to how they receive power. Device Type Description Selfpowered Devices that rely on their own power supply (in other words, you plug them into an AC outlet) are self-powered devices (sometimes called active devices). All devices that draw more than 500 ma of power are required to be self-powered. USB cables have wires to carry both power and data. Bus-powered (sometimes called passive) devices get their power from the USB cable. Bus-powered devices are classified as low-powered or high-powered devices depending on the amount of power they draw from the USB bus. Bus powered Low powered devices use 100 ma or less High-powered devices use between 100 and 500 ma Like USB devices, USB hubs can be bus-powered or self-powered. You cannot connect high-powered devices to a bus-powered hub (you can only connect lowpowered or self-powered devices to a bus-powered hub). Therefore, self- 11

12 powered hubs that provide 500 ma per port are recommended to ensure an adequate power supply to all bus-powered devices that you may wish to connect to the hub. To install a USB device, you typically install the software driver before attaching the device. When you plug in the device, it will be automatically detected and configured. Lecture Focus Questions: What are the differences between USB 1.1 and 2.0? What types of devices are typically self-powered? Bus powered? What are the power requirements for a low-powered and high-powered bus powered-device? Where do you typically connect the B end of a USB cable? Section 4.4: IEEE 1394 (Firewire) The IEEE 1394 standard is a set of specifications for a high-performance serial bus. The generic IEEE 1394 standard is called HPSB (High Performance Serial Bus). Be aware that some companies market their IEEE 1394-based products under trademarked names, most notably: Firewire: Firewire, trademarked by Apple Computers, Inc. and the basis of the IEEE 1394 standard i.link, trademarked by Sony Corporation Lynx, Texas Instruments Uses a serial bus using twisted-pair wiring for data transport. Lets you connect up to 63 devices on one IEEE 1394 bus. Supports many kinds of isochronous devices (devices requiring additional bandwidth to accommodate streaming data), such as digital video cameras and recorders, hard drives, and network adapters. Supports Plug-and-Play and hot-swapping (you can add and remove devices without rebooting). Can provide power (up to certain limits) to devices. Supports peer-to-peer transfers. For example, data can be transmitted between a digital video camera and a recording device without going through a computer. The following table describes the details of common IEEE 1394 standards. Version Description 1394 Supports speeds of 100, 200, 400 megabits per second Maximum cable length is 4.5 meters (15 feet) 12

13 1394.A Clarifies and enhances the original standard B Supports speeds of 800, 1600, and 3200 megabits per second Maximum cable length is 100 meters (328 feet) Also called Firewire Supports peer-to-peer data transmission Devices like scanners and digital cameras can send data directly to a printer (no computer involvement required) You should know the following facts about IEEE 1394: An IEEE 1394 bus does not necessarily include a PC. In other words, various types of devices can potentially act as the root node. The devices on the bus decide the root node each time a device is added or removed from the bus. The maximum number of hops (other devices) between any two devices is 16. You cannot connect IEEE 1394 devices to form a loop. IEEE 1394 devices can be bus powered or self powered. IEEE 1394 cables with four wires are not self-powered; IEEE 1394 cables with six wires are self-powered. The following table shows the common IEEE 1394 cables and connectors. Connector Cable cross-section 6-pin connector 13

14 4-pin connector Lecture Focus Questions: What are the additional functions of a six-wire IEEE 1394 over a four-wire IEEE 1394 cable? What is the maximum cable length of an IEEE 1394 cable? What are common devices that use IEEE 1394? Section 4.5: Display Devices CRT monitors use an electron beam that hits phosphor dots inside of a vacuum tube. While it is possible for a CRT monitor to have a digital connection, virtually all CRT monitors connect to the video card using a DB-15 (also called a D-sub) connector. Be aware that the display qualities of your monitor depend on the capabilities of both the monitor and the video card. When choosing a CRT monitor, keep in mind the following considerations. Consideration Description Screen size is often expressed in two different measures: Screen size The physical screen size (also called the actual size). This is the diagonal measure of the display tube. The effective viewing size identifies the largest image size that can be displayed. Because of how the CRT monitor works, portions of the display tube cannot be used for displaying the image. Graphic artists, multimedia designers, and programmers often need much larger displays. Resolution The resolution is the number of pixels available on a display screen. Specifically, the resolution is described by the amount of pixels horizontally across the display by the amount of pixels vertically down the display. Monitors that support a higher resolution can display higherquality graphics or have a larger screen area. 14

15 There are two methods of controlling the illumination of the phosphor: Display type A shadow mask consists of a metal screen full of holes that are aligned with each dot. The screen shields the electron beam from illuminating between dots and leaves an outline around each pixel. An aperture grill consists of a screen of ultra-thin vertical and horizontal wires. This configuration allows more electrons through resulting in a richer color display. On an aperture grill monitor you might be able to see two horizontal lines running across the display. These lines are the wires that are used to dynamically change the grill opening. Dot pitch The dot pitch is the distance between pixels. This is measured in millimeters. The standard dot pitch in color monitors in about.15 mm to.30 mm. The smaller the dot pitch, the more room there is for higher resolutions and the sharper a picture may be. Refresh rate Interlacing The refresh rate is the amount of time required for the CRT's electron beam to paint the screen from top to bottom. Increasing the refresh rate reduces screen flicker. Refresh rates are measured in Hz. Interlacing is drawing the screen in two passes; odd lines on the first and then the even lines on the second pass. Non-interlaced monitors produce the least amount of flicker. Additional monitor features include: Additional features Green monitors that are Energy Star or Green Star compliant. These monitors use less than 30 watts and reduce power consumption by 99% when in sleep or suspended mode. Flat displays (tube monitors with a flatter glass tube). A flatter display results in an image with less distortion around the edges. Built in speakers or USB hub. CRT monitors have a 4:3 aspect ratio, which matches the display ratio of a television set. The magnetic field used for drawing the image on the screen can cause a buildup of magnetism on internal monitor components. This magnetic field can cause color distortions, especially around the edges. To correct this problem, use the degauss feature of the monitor. Degaussing creates an oscillating magnetic field for a short period of time. Most monitors perform degaussing automatically when they are turned on, but you can also manually initiate degaussing using the monitor's front panel controls. LCDs are flat panels that use a liquid crystal material and transistors to display images. TFT (thin film transistor) and active matrix are additional terms that are often used to describe LCD monitors. Currently, all LDC displays are TFT and active matrix displays. The following table describes various characteristics of LCD monitors. 15

16 Factor Description As you compare LCD monitors, you will see the following characteristics that describe the characteristics of the display: Display characteristics The contrast ratio refers to the difference in light intensity between the brightest white and the darkest black. An example contrast ratio is 1000:1. A higher initial number indicates a better quality picture. o The static contrast ratio indicates the difference that can o be displayed at the same time. The dynamic contrast ratio indicates the difference that the monitor is capable of producing. The response time indicates how quickly a pixel can go from black, to white, and back to black. The response time is indicated in milliseconds (ms). A quicker response time is needed when viewing moving images such as video or games. A response time that is too slow (above 8ms) results in ghosting or blurred images. Most manufactures have started using a grey-to-grey (G2G or GTG) measure of response time, which makes the response time faster than a white-to-black response time. Brightness or luminance identifies the amount of light the monitor produces (how bright it is). Brightness is measured in candelas per square meter (cd/m2 also called a Nit), with a higher number indicating a brighter screen. A brighter screen is typically desired for watching movies, or on laptops where the screen is viewed in full sunlight. The viewing angle identifies the angle at which the image can still be seen. With LCD monitors, the image will be dimmer and colors distorted when viewed from an angle. The viewing angle is described with two numbers: horizontal angle and vertical angle, with a higher number being better. The pixel pitch is the distance between pixels. A lower number means a sharper image and possibly higher resolutions. LCD monitors use one of the following technologies: Display type Twisted Nematic (TN) panels are the most common type used in computer monitors, especially in smaller sizes. TN panels have very good response times (2ms to 5ms), so are well-suited for games with a lot of motion. o TN panels have poor color reproduction due to the fact that only 6-bits per color can be displayed. They mimic o true 24-bit color using dithering and other techniques. TN panels have worse viewing angles and contrast ratios than the other display types. Vertical Alignment (VA) panels offer the best contrast ratios of the display types, and are well suited for movies that require good contrast. o VA panels have better color reproduction and wider viewing angles than TN displays, but with slower 16

17 response times and a higher cost. o VA panels suffer from color shift that produces uneven colors across the display with loss of detail in dark scenes. In Plane Switching (IPS) panels have the best color reproduction quality and viewing angles of the display types, and are well suited for graphic design where full and accurate color representation is required. o o IPS panels have relatively slow response times (6ms to 16ms), and have a slight purple tint in blacks when viewed from a wide angle. IPS panels are the most expensive type of panel, and could be difficult to find. Because CRT monitors have better color reproduction than TN monitors and are cheaper than IPS monitors, CRT monitors are still used by many graphic artists. The LCD backlight provides the light that makes the individual pixels visible. The light itself is actually along the top, bottom, and/or sides, with a special layer that reflects the light throughout the display. There are currently two methods used for the backlight: Backlight method Cold Cathode Fluorescent Lamp (CCFL) is currently the most common backlight source. CCFL backlights require an inverter to provide AC power to the backlight. Light Emitting Diode (LED) backlights provide brighter screens, lower power consumption, a wider color range, greater contrast, and mercury-free construction. LEDs use DC power, eliminating the need for an inverter. The aspect ratio is the ratio of the width and the height. Aspect ratio Normal displays have a 4:3 aspect ratio (used in CRT displays). Widescreen displays have a 16:10 aspect ratio. HDTV screens have a 16:9 aspect ratio. If you watch HDTV content (DVD movies) on a 16:10 monitor, the display will either be stretched slightly or have black bars (areas without video content) on the top and the bottom. If you want to optimize DVD viewing from your computer, consider purchasing a monitor with a 16:9 aspect ratio. Resolution The resolution is the number of pixels, and is expressed using two numbers: the number of horizontal rows and vertical columns. It is common for CRT monitors to support a wide number of resolutions, but LCD monitors often have a native (optimum) display resolution. Although you might be able to change the resolution to a different setting, the results may not be satisfactory. Common resolutions are often described using a naming standard, 17

18 although these standards encompass much more than just resolution size. VGA = 640 x 480 SVGA = 800 x 600 XGA = 1024 x 768 XGA+ = 1152x864 SXGA = 1280x1024 (5:4 aspect ratio) SXGA+ = 1400x1050 WSXGA+ = 1680 x 1050 UXGA = 1600 x 1200 WUXGA = 1920 x 1200 Resolutions with a W in the name are widescreen resolutions with a 16:10 aspect ratio. In addition to these standard resolutions, you can also purchase monitors with the 16:9 aspect ratio used by HDTV content. Increasingly, the difference between an LCD monitor and an HDTV is being blurred. You can purchase an HDTV that can also function as a monitor, or a monitor that can function as a TV. Resolutions used by HDTV are: 1280 x x 1080 HDTV support Full HD content is designed for a resolution of 1920 x 1080 using progressive scanning (where each line on the screen is redrawn in order). Full HD support is therefore referred to as 1080p. Cheaper TVs and monitors at lower resolutions or using interlacing (where every other line is drawn with each pass) are not capable of displaying all of the video content in full HD. 720p (1280 x 720 progressive scan) and 1080i (1920 x 1080 with interlacing) identify displays that do not support full HD content, with both 720p and 1080i being comparable in quality. LCD monitors often include the following features for HDTV support: An HDMI input that accepts both video and audio input through the HDMI port Built-in speakers and audio-out to external speakers An HDTV tuner to allow you to watch TV and change channels when the monitor is used as a TV Support for HDCP to watch copy-protected content Monitor size is typically described using a diagonal measurement. Screen size CRT monitors will typically list the monitor size along with the viewable image size which is smaller than the total screen size. Because of how the CRT monitor is made, not all of the available screen size can actually display an image. LCD monitors use a single value for the screen size. LCD monitors can use the entire screen for displaying images. 18

19 Because of the difference in effective viewing size, you can often purchase a smaller LCD monitor and get the equivalent viewing size of a larger CRT monitor. For example, you can replace a 19" CRT monitor with a 17" LCD monitor and have about the same effective viewing size. LCD displays are very delicate and occasionally a pixel fails to display properly (called a dead pixel). Dead pixels Having a few dead pixels can be common on many displays. Most manufactures have a minimum number of dead pixels that must exist before they will consider an exchange. In addition, some place limitations on where the dead pixels must be located in order to qualify. If you are concerned about dead pixels, review the return policy before purchasing. Pressing lightly on the screen may revive the pixel. Debris on the screen can be mistaken for a dead pixel. There are utilities to identify and possibly fix dead pixels on a monitor. Filters One of the chief drawbacks of LCD monitors is the fact that they are susceptible to glare because of the flat nature of screen. The glare can make it difficult to view the display on the monitor. You can install an antiglare filter to reduce the glare reflected from the surface of an LCD display. (Anti-glare filters can be used with CRT, LED, and plasma monitors as well.) For security purposes, you can also implement a privacy filter (sometimes called a privacy screen) on LCD monitors. Privacy filters significantly decrease the viewing angle of an LCD monitor, preventing it from being viewed from the side. An LED-based monitor is a special type of LCD monitor. It still uses a liquid crystal display to create images on the screen. However, it uses a different type of backlight than that used in a standard LCD. Traditional LCD monitors use cold cathode florescent (CCFL) tubes to illuminate the display. LED monitors replace the CCFL tubes with LED backlight technology. LED monitors have several advantages over LCD monitors: LED monitors can display more colors more accurately than standard LCD monitors. LED monitors can be manufactured using smaller, thinner dimensions. LEDs use DC power, eliminating the need for an inverter. LED monitors typically consume much less electricity than standard LCDs. LED backlights don't contain mercury, as CCFLs do. There are several types of LED monitors: LED Monitor Type Description 19

20 Edge-lit backlights using white LEDs (EL- WLED) EL-WLED monitors are the least expensive, smallest, and most widely used type of LED monitor. White LEDs are implemented along the edge of the monitor behind the liquid crystal display. The LEDs are installed along on only one edge of the monitor, not all four. The light is spread over the entire screen using a diffuser. RGB LED RGB LED monitors implement RGB LEDs across the entire surface of the display panel. Each individual LED is capable of producing red, green, or blue light, allowing the monitor to display more colors with more accuracy than EL-WLEDs can. This performance comes at a cost, however. RGB LED monitors are much more expensive than EL-WLED monitors to manufacture. In addition, the construction of the displays doesn't allow them to be built as small or as thin as EL-WLED monitors. Organic Light- Emitting Diode (OLED) OLED monitors implement a film of organic compound between two electrodes. When current is applied to the electrodes, the organic compound emits light. OLED monitors are more efficient, offer a wider viewing angle, and provide faster response times. However, they are costly to manufacture. Currently, OLED panels are the most expensive type of LED panel. In addition, they don't last as long as other types of LED panels. Plasma monitors function using a completely different technology as compared to LCD and LED monitors. Plasma displays utilize small cells that contain electrically-charged ionized gases. A plasma panel is made up of millions of these cells sandwiched between two panels of glass. When electrical current is applied to a plasma cell, the gas within the cell forms a plasma and emits a photon of light. Each photon strikes a phosphor painted on the inside of the cell, allowing different colors to be displayed. Each pixel in a plasma display is made up of three cells; red, green, and blue. As with LED monitors, plasma monitors don't require a backlight. Plasma displays have several advantages: Plasma monitors usually display colors more accurately than LCD monitors. For example, the color black is displayed more accurately on a plasma display than on an LCD display. The color contrast is usually better on a plasma monitor. Motion blur is reduced on a plasma monitor because of its faster response time. Plasma displays also have several disadvantages: Plasma displays consume two to three times as much power as LED and LCD displays. They generate much more heat than LED or LCD displays. They are sensitive to altitude changes due to changes in air pressure. You should be familiar with the following video interfaces. Interface Description 20

21 D-sub Cable Female port The D-sub connector, sometimes called a VGA connector, uses a DB-15 connector with three rows of pins. The D-sub connector on a video card provides analog output. You can connect the following monitors to a video card with a D-sub connector: Analog CRT monitor. LCD monitor that accepts an analog connection. Some LCD monitors have a D- sub connection, or you might need a cable with a D-sub connection on one end and a DVI-A connection on the other end to connect to the LCD monitor. DVI-A Cable A DVI-A (digital video-analog) connection on a video card provides analog output. DVI-A connections are rarely (if ever) used for computers monitors, but might be used on some HDTV systems. You can connect the following monitors to a video card with a DVI-A connector: Analog CRT monitor. Use a cable with a D-sub connection on one end and a DVI-A connection on the other end to connect to the monitor. LCD monitor that accepts an analog connection. Some LCD monitors have either a D-sub or a DVI-A connection. DVI-D Single link cable Dual link cable Female port A DVI-D (digital video-digital) connection on a video card provides digital output. DVI-D connections are rated as either single link or dual link: Single link connectors have 3 rows of 6 pins with one additional larger horizontal pin. Single link can support 60 Hz up to 1920x1080 resolution. Dual link connectors have 3 rows of 8 pins plus the horizontal pin (often called a 25-pin, pin, or 24-pin connector). Dual link can support 60 Hz up to 2048x1536 resolution. Dual link allows for longer cable lengths and a higher video resolution. When choosing a video card, choose a card that supports dual link whenever possible. You can only connect a digital monitor to a DVI-D connector. Connecting an analog monitor, such as a CRT monitor, is only possible by using a special 21

22 converter box. If the video card only has a DVI-D connector and you have an analog-only monitor, it is often cheaper to purchase a new video card instead of the converter box. CRT monitors with DVI-D connectors are possible but rare. This means that the CRT monitor accepts digital input. DVI-I Single link cable Dual link cable A DVI-I (digital video-integrated) connection on a video card provides both analog and digital output. The DVI-I connection has all of the pins present in both the DVI-A and DVI-D connections. Most video cards and many LCD monitors have a DVI-I connection. You can connect the following monitors to a video card with a DVI-I connector: Analog CRT or LCD monitor using a cable with a D-sub connection on one end and a DVI-A connection on the other end. LCD monitor with either a DVI-I or DVI-D connection. Female port DMS-59 Female port The DMS-59 connector is used to allow multiple video ports from a single connection. The DMS-59 connector: Is typically included on slimline video cards that can have only a single port. Sends out two separate DVI-I signals through the single connector. Uses a special cable that splits the signal into separate video interfaces. For example, the cable might split the signal into two DVI-I connectors, two D-sub connectors, or one DVI-I connector and one D-sub connector. Composite video Cable Female port A composite video connection on a video card provides analog, video-only TV output. Composite video connectors are RCA connectors (typically yellow). Composite signals combine three qualities of video into a single signal: The Y channel is for brightness or luminance U and V channels provide color information Use the composite connection to connect a TV, VCR, or video camera to the video card. Audio signals must be 22

23 supplied separately. S-video Cable S-video (separate-video, Y/C, or S-VHS) connections are present on many video cards and supply analog, video-only TV output. The s-video connector is a 4-pin mini-din connector that has two separate channels, one for Y (luminance) and one for UV (color). S-video can easily be converted to composite video by combining the Y and UV channels into a single signal. Female port HDTV (Component) Female port HDMI Cable connector An HDTV connector supplies analog, video-only TV output in three separate channels: R (red), G (green), and B (blue). The HDTV connector uses a 7-pin minidin cable. Video cards with HDTV output typically include a conversion cable that converts the 7-pin connector into three RCA cables for connecting to an HDTV device. As with composite and s-video, audio must be supplied to the device separately. High-Definition Multimedia Interface (HDMI) is a digital video and audio connector used for high-definition digital audio and video. HDMI combines the audio and video signals onto a single cable. You might use HDMI connectors in the following configurations: You can use a DVI-to-HDMI cable to connect the DVI-D output from a video card to a monitor or an HDTV device that has an HDMI connector. However, this configuration only supplies video, and not audio, to the display device. (DVI and HDMI are electrically equivalent, meaning that a simple pin-to-pin adapter is all that is required to connect a DVI device to an HDMI port.) You can purchase a video card with an HDMI connector. Many of these video cards have an audio input port that accepts digital audio into the video card where the audio signals are combined with the video signals and sent out the HDMI port. In this configuration, the video card does not process the audio, but simply passes it through the video card from the external source and onto the HDMI output. There are actually four different HDMI connector types, including a mini-hdmi connector; the one shown is the most common. 23

24 DisplayPort DisplayPort is an alternative to an HDMI connector. DisplayPort uses a different signal format than DVI or HDMI. However, DisplayPort supports sending DVI or HDMI signals over the same port using a simple adapter. DisplayPort uses a digital-only signal. To connect a VGA monitor to a DisplayPort, you will need a special active converter that reformats the signal for analog devices. Like HDMI, DisplayPort can send audio signals over the same cable (if audio is supported by the video card and monitor). DisplayPort uses lower voltage than DVI and HDMI. DisplayPort is also an internal video interface used by laptop displays to interface with internal video cards. For manufacturers, the DisplayPort is royalty free, whereas including an HDMI connector requires a fee for each connector used. Manufacturers such as Dell and Apple are starting to use DisplayPorts in monitors and video cards, but DisplayPorts are not yet used on HDTV sets. Cable TV (F-type) Cable Female port Video cards and monitors with a built-in TV tuner have an F-type cable TV connector. Most video cards that provide cable TV input also include audio output. However, most of these cards do not provide analog or digital monitor output. Do not confuse video in, which can be supplied by composite, s-video, or HDTV connectors, with TV-tuner capabilities. The built-in tuner means that the card or monitor itself has the ability to accept multi-channel input and change the display by changing the channel. Without a built-in tuner, video input is limited to a single channel, and changing TV channels must be done at the source device before inputting into the video card. When connecting various devices to a computer video card, you can typically find converter cables to match the interface on the video card with the interface on the device. However, these cables do not convert from analog to digital signaling. In addition to the connectors shown in the table above, you may also run into video-in ports on video capture boards that utilize BNC connectors. BNC video connectors are used in two configurations: Yellow BNC connectors are used to transmit composite colors. In this configuration only a single cable is required to transmit the video signal. Red, green, and blue BNC connectors are used to transmit a single color. In this configuration, three separate cables are required to transmit the video signal. 24

25 After you have installed a video adapter, install the device drivers and use the Windows Display applet to configure various settings for both the monitor and the video adapter. An easy way to open the Display settings is to: On Windows XP, right-click the Desktop and choose Properties. On Windows Vista/7, right-click the Desktop and choose Personalize, then select Display Settings. The following table describes various settings you can configure: Setting Description The resolution is the number of pixels available on a display screen. The resolution is expressed using two numbers: the number of pixels horizontally across the display by the number of pixels vertically down the display. A higher resolution means that more information can be shown on the screen at a time. Common resolutions are often described using a naming standard, although these standards encompass much more than just resolution size. VGA = 640 x 480 SVGA = 800 x 600 XGA = 1024 x 768 XGA+ = 1152x864 SXGA = 1280x1024 (5:4 aspect ratio) SXGA+ = 1400x1050 WSXGA+ = 1680 x 1050 UXGA = 1600 x 1200 WUXGA = 1920 x 1200 Resolution Be aware of the following when configuring the resolution: Resolutions with a W in the name are widescreen resolutions with a 16:10 aspect ratio. In addition to these standard resolutions, you can also purchase monitors with the 16:9 aspect ratio used by HDTV content. Resolutions used by HDTV are: o 1280 x 720 o 1920 x 1080 Full HD content is designed for a resolution of 1920 x 1080 using progressive scanning (where each line on the screen is redrawn in order) and is referred to as 1080p. Cheaper TVs and monitors at lower resolutions or using interlacing (where every other line is drawn with each pass) are not capable of displaying all of the video content in full HD. 720p (1280 x 720 progressive scan) and 1080i (1920 x 1080 with interlacing) identify displays that do not support full HD content, with both 720p and 1080i being comparable in quality. 25

26 It is common for CRT monitors to support a wide number of resolutions, but LCD monitors often have a native (optimum) display resolution. For best results, configure LCD monitors to use the native resolution. The color depth is the number of different colors that can be displayed on the screen at a time. Color depth is expressed in bits (a higher bit count increases the number of colors that can be displayed). Common bit depths include: Color depth 8-bit (256 possible colors) 16-bit, also called high color (65,536 possible colors) 24-bit, also called true color (16.7 million possible colors) 32-bit, also called true color (16.7 million possible colors and alpha channel) When you have multiple monitors, edit the Display settings to configure how content is shown on each monitor. Monitor relationship Check the Extend desktop onto this monitor option to show desktop content on the monitor. One monitor is identified as the main monitor by selecting the This monitor is my main monitor option. This monitor displays the Start menu and Task Bar. You can configure each monitor with different resolution and color depth settings. By default, Windows places the first monitor it detects on the right. Drag the monitor icons to change the logical position to match the physical position of each monitor. Click the Identify Monitors button to display the monitor number as identified by Windows. The refresh rate is the number of times the entire screen repaints per second. Refresh rate Refresh rates are measured in Hz. Most monitors support multiple refresh rates. Increasing the refresh rate reduces screen flicker. A desirable range of refresh rate is 75 Hz or higher. Overall, LCD monitors have lower refresh rates than CRT monitors. Higher refresh rates are not required because of the better quality of the LCD displays. A refresh rate of 70 Hz or lower on a CRT monitor may cause eye fatigue. The refresh rate must be supported by the video card and the monitor. If you are unable to set a high refresh rate that is supported by your monitor, you might need to upgrade the video card to one with more memory. 26