Supporting IO Devices

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Chapter 9

• Supporting I/O Devices

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You Will Learn

• How to use standard resources on a computer
  system when installing add-on devices
• How to resolve resource conflicts
• How to install a new device on a computer
• About keyboards, pointing devices, and video
  subsystems

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Basic Principles of Peripheral Installations

• When you add a new peripheral to a computer, the
  device needs
• A device driver or BIOS
• System resources
• IRQ
• DMA channel
• I/O addresses
• Upper memory addresses
• Applications software

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Fundamental Installation Principles

• Install both hardware and software
• The peripheral is a hardware device controlled by
  software
• Install at all levels of software
• Be aware of possible system resource conflicts
• The same IRQ
• The same DMA channel
• The same I/O address
• The same upper memory addresses (for 16-bit
  drivers)

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A Review of System Resources

• IRQ
• DMA channel
• I/O addresses
• Upper memory addresses

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Installation Overview

• Install the device
• Install the device driver
• Install the applications software

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Hardware Devices

• Internal (installed inside computer case)
• Drives (hard drives, floppy drives, CD-ROM
  drives, DVD drives, Zip drives)
• Devices that are inserted in expansion slots on
  the system board (modem card, video capture card)
• Usually less expensive and take up less desk
  space than external devices
• External (installed outside the case)
• Existing port (serial, parallel or USB)
• Interface card installed in expansion slot

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Embedded BIOS on Devices

• Sometimes a BIOS parameter may need to be changed
  to prevent a conflict in the assignment of
  computer resources

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Embedded BIOS on Devices
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Embedded BIOS on Devices
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Device Drivers

• Two kinds
• 16-bit real mode drivers
• 32-bit protected-mode drivers (Windows 9x)
• Device drivers under DOS
• Mouse driver common 16-bit DOS device driver
• Device drivers under Windows 9x
• Installed when hardware device is installed
• Information kept in Windows 9x Registry
• Automatically execute each time Windows 9x starts

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Device Drivers under Windows 9x
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Device Drivers under Windows 9x
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Device Drivers under Windows 9x
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Device Drivers under Windows 9x
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Using Ports and Expansion Slots for Add-on Devices

• Serial ports
• Parallel ports
• USB ports
• IEEE 1394 ports
• Expansion cards plugged into PCI or ISA expansion
  slots

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Using Serial Ports

• Transmit data in single file
• Identified by number of pins (9 or 25)
• Almost always male

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Serial Ports
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Serial Ports
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Serial Ports
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Infrared Technologies

• An infrared transceiver that supports infrared
  devices, such as wireless keyboards and printers,
  can connect directly to a serial port
• The transceiver uses resources of the serial port
  for communication and creates a virtual infrared
  serial port and virtual infrared parallel port
  for infrared devices
• Some system boards provide a 5-pin connection for
  its own proprietary IRDA-compliant infrared
  transceiver

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The UART Chip

• UART universal synchronous receiver/transmitter
• Controls all 9 pins of a serial port
• Sets communications protocol
• Converts parallel data bits received from the
  system bus into serial bits
• Driver for the UART 16550 is built into Windows 9x

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UART Driver
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UART Driver
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Serial Ports Summary

• Used for various input/output data transfers,
  (data transferred over modems, to mice, to
  printers, and to other computers)
• Follow RS-232C industry standard for
  communication
• Assigned unique IRQ and unique I/O address
• UART chip controlling the port is partially
  responsible for the speed of the port

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Using Parallel Ports

• Transmit data in parallel, 8 bits at a time
• Almost always female
• Commonly used by printers
• IEEE 1284 standards for parallel ports require
  backward compatibility with previous technology

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Types of Parallel Ports

• Standard parallel port (SPP)
• Enhanced parallel port (EPP)
• Extended capabilities port (ECP)

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Standard Parallel Port

• Sometimes called a normal parallel port or a
  Centronics port
• Only allows data to flow in one direction
• Slowest of the three types of parallel ports

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Standard Parallel Port
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Enhanced Parallel Port (EPP)

• Bi-directional
• Faster than original parallel ports on PCs that
  only allowed communication in one direction
• Covered under the IEEE 1284 specifications

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Extended Capabilities Port (ECP)

• Bi-directional
• Designed to increase speed over EPP by using a
  DMA channel
• Covered under the IEEE 1284 specifications

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Configuring Parallel Ports

• Setup can have up to three different settings for
  parallel ports

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Examining a General-purpose I/O Card

• Designed for use with a system board that does
  not have serial or parallel ports, or floppy
  drive or hard drive connections
• Not Plug-and-Play compliant

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Examining a General-purpose I/O Card
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Installing a General-purpose I/O Card
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Using USB Ports

• Easier than parallel or serial ports because USB
  controller (with support from OS) manages USP
  port resources
• All USB ports and USB devices (up to 127)
  connected to them use a single IRQ, I/O address,
  and DMA channel

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USB Versions

• Current version of the USB standard is version
  1.1, which supports speeds up to 12 Mbps
• USB 2.0 is expected soon and will support speeds
  up to 480 Mbps

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USB

• Transfers data in packets and can partly improve
  the speeds of serial and parallel ports because
  it uses higher quality cabling
• Cable has four wires
• Two for data
• One for ground
• One provides up to five volts of power to the
  device

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Requirements for Installing a USB Device

• System board or expansion card that provides a
  USB port and USB firmware
• OS that supports USB
• USB device
• USB device driver

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Installing a USB Device

• Using Device Manager, verify that the USB host
  controller driver is installed under Windows 9x
• Plug in the USB device and install its device
  driver
• Install the applications software to use the
  device

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Verifying that the USB Host Controller Is
Installed
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Using IEEE 1394 Ports

• The IEEE 1394 bus
• Provides either a 4-pin or 6-pin connector
• Uses only one set of system resources
• Is hot-pluggable

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Types of IEEE 1394 Cable Connectors
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IEEE 1394

• Uses isochronous data transfer, an ideal medium
  for data transfers between consumer electronics
  products

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IEEE 1394 Standards

• Current standard IEEE 1394.A
• Supports speeds of 100, 200, or 400 Mbps
• Allows for cable lengths up to 4.5 meters
• Is hot-pluggable
• Under development IEEE 1394.B
• Will support speeds up to 3.2 gbps
• Will allow cable lengths up to 100 meters

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To Use a 1394 Port

• Using Device Manager, verify that Windows 98
  recognizes that an IEEE 1394 controller is
  present on the system board
• Plug the device into the 1394 port install the
  device drivers for the 1394-compliant device
• Install the applications software to use the
  device

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Using PCI Expansion Slots

• Up to four slots are supported by the PCI bus
• Often white in color
• Faster than ISA bus often used for fast I/O
  devices like video or network cards

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PCI Expansion Slots
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PCI Expansion Slots
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PCI Bus IRQ Steering

• Makes it possible for PCI devices to share an IRQ
• System BIOS and the OS must both support this
  feature

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PCI Bus IRQ Steering
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Using ISA Expansion Slots

• Configuration is not as automated as USB or PCI
• ISA bus itself does not manage the system
  resources, as do the USB and PCI bus masters
• ISA device must request system resources at
  startup
• Often black in color

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When Device Installations Create Problems

• Likely due to a resource conflict
• Resolving resource conflicts
• Know system resources already in use
• Know what resources the new device will need
• Install the device using resources not already
  used by your system
• If a conflict, use MSD, Device Manager, CMOS
  setup, and documentation for system board and
  devices to identify and resolve the problem

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Resolving Resource Conflicts
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Once You Have Found the Conflicting Resource

• If the device is a legacy ISA device, physically
  set the devices jumpers or DIP switches to use a
  different resource
• If a legacy device can only use one IRQ, then use
  CMOS setup to reserve that IRQ for the device
• If your PC supports PCI bus IRQ steering, enable
  the feature

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Once You Have Found the Conflicting Resource

• Using PCI bus IRQ steering, tell Windows 98 to
  use a different IRQ for a PCI device
• Use CMOS setup to assign a specific IRQ to a PCI
  device
• Move the PCI device to a different slot, which
  will cause the PCI bus to assign a different
  resource to the device
• Disable PCI bus IRQ steering

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Essential I/O Devices for a PC

• Keyboard
• Pointing device
• Video display

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Keyboards

• Design
• Traditional straight design
• New ergonomic design

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Keyboards Layouts

• Original IBM PC keyboard
• Keyboard controller chip on keyboard
• Not compatible with AT and later
• AT keyboard
• Enhanced AT keyboard
• Key layout
• QWERTY
• Dvorak

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Keyboard Connectors

• PS/2 connector (mini-DIN)
• Six pins
• DIN connector
• Round with five pins
• USB port
• Cordless

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Two Common Keyboard Connectors
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Pinouts for Keyboard Connectors
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Keyboard Connector Adapters
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Pointing Devices
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Two Mouse Technologies

• Wheel mouse
• Optical mouse

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How a Wheel Mouse Works
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Methods of Mouse Connection

• Use the serial port (serial mouse)
• Use a dedicated round mouse port coming directly
  from the system board (system-board mouse or PS/2
  compatible mouse)
• Use a mouse bus card that provides the same round
  mouse port (bus mouse)
• Use the USB port
• Use a Y-connection with keyboard
• Use a cordless technology

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Cleaning the Mouse

• Remove the cover
• Clean the rollers with a cotton swab dipped in a
  very small amount of liquid soap

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Other Pointing Devices

• Trackballs
• Touch pads

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Computer Video

• Primary output device of a computer is the
  monitor
• Two necessary components for video output
• Video controller
• Monitor

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Monitors

• Rated by screen size, resolution, refresh rate,
  interlace features
• Most meet standards for Super VGA
• Use either older CRT technology or new LCD
  technology

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How a CRT Monitor Works
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Choosing the Right Monitor
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Monitor Controls

• Horizontal Size
• Horizontal Position
• Vertical Size
• Vertical Position
• Brightness
• Contrast
• Keystone or Squareness

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Flat Panel Monitors

• Are built to receive either an analog signal or a
  digital signal from the video card and have two
  ports on the monitor to accommodate either signal

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Flat Panel Monitors

• Compared to CRT monitors they
• Take up much less desk space
• Are lighter
• Require less electricity to operate
• Provide a clearer, more precise image
• Cost three times more

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Layers of the LCD Panel
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LCD Panels on the Market

• Active-matrix
• A transistor that amplifies the signal is placed
  at the intersection of each electrode on the
  grid, which further enhances pixel quality
• Dual-scan passive matrix
• Two columns of electrodes are activated at the
  same time
• Less expensive and does not provide as
  high-quality an image as active-matrix display

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Video Cards

• Provide interface between monitor and computer
• Also called graphic adapters, video boards,
  graphics cards, display cards
• Main features to look for in a video card
• The bus it uses (influences speed and
  performance)
• Amount of video RAM it has or can support

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How a Video Card Works
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The Bus Used by the Video Card

• Since 1995, video cards have been designed to use
  only the PCI bus and more recently to use the AGP
  slot
• Older video cards were made to run on VESA local
  buses (VL-bus), a proprietary local bus, ISA
  buses, and EISA buses
• The fastest bus for video on a system board today
  is AGP with a 32-bit-wide data bus, running at up
  to 1 GB/sec

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Video Card Performance

• Performance on the video card is affected by
• Chip set
• Memory
• RAM DAC
• Bus speed and size
• Methods of improving performance
• Dual-porting
• Place a processor on the video card to make it a
  graphics accelerator

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Graphics Accelerator

• A type of video card that has its own processor
  to boost performance
• Necessary with the demands that graphic
  applications make in the multimedia environment
• Processor is specifically designed to manage
  video and graphics
• Their features reduce the burden on the system
  board CPU and perform the function much faster
  than the system board CPU

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Video Memory

• Necessary to handle large volume of data
  generated by increased resolution and color
• Stored on video cards as memory chips

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How Much Video Memory Is Needed?

• Determined by
• Screen resolution (measured in pixels)
• Number of colors (color depth)
• Enhancements to color information called alpha
  blending

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Memory Needed to Hold the Frame Buffer
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Types of Video Memory

• VRAM (video RAM)
• MDRAM (multibank DRAM)
• SGRAM (synchronous graphics RAM)
• WRAM (Window RAM)
• 3D RAM

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Chapter Summary

• Procedures and guidelines common to most
  installations of I/O devices
• How to use serial, parallel, USB, IEEE 1394
  ports, and expansion slots
• Essential I/O devices for a PC
• Keyboard
• Pointing device
• Monitor

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