Essential i o devices for a pc
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Essential I/O Devices for a PC Keyboard Pointing device Video display Keyboards Design Traditional straight design New ergonomic design Correct Position at the Keyboard Keyboards Two common technologies in the way the keys make contact Foil contact Metal contact Logical progression

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Essential I/O Devices for a PC

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Essential I/O Devices for a PC

  • Keyboard

  • Pointing device

  • Video display


Keyboards

  • Design

    • Traditional straight design

    • New ergonomic design


Correct Position at the Keyboard


Keyboards

  • Two common technologies in the way the keys make contact

    • Foil contact

    • Metal contact

  • Logical progression

    • Make code

    • Break code


Keyboard Connectors

  • PS/2 connector (mini-DIN)

    • Six pins

  • DIN connector

    • Round with five pins

  • USB port

  • Cordless


Pinouts for Keyboard Connectors


Two Common Keyboard Connectors


Keyboard Connector Adapters


Pointing Devices


Two Mouse Technologies

  • Wheel mouse

  • Optical mouse


How a Wheel Mouse Works


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


Cleaning the Mouse

  • Remove the cover

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


Other Pointing Devices

  • Trackballs

  • Touch pads


Computer Video

  • Primary output device of a computer is the monitor

  • Two necessary components for video output

    • Video controller

    • Monitor


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


How a CRT Monitor Works


Choosing the Right Monitor


Monitors and ELF Emissions

  • ELF emissions = extremely low frequency emissions (of magnetic fields)

  • Most monitors comply with the MPR II standard; very few comply with the more stringent TCO ’95 standards


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


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


Layers of the LCD Panel


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


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


How a Video Card Works


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

    • Regular AGP slot: 132 pins

    • AGP Pro: 188 pins


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


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


Graphics Accelerator Features

  • MPEG decoding

  • 3-D graphics

  • Dual porting

  • Color space conversion

  • Interpolated scaling

  • EPA green PC support

  • Digital output to flat panel display monitors

  • Applications support for popular high-intensity graphics software


Video Memory

  • Necessary to handle large volume of data generated by increased resolution and color

  • Stored on video cards as memory chips


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


Memory Needed to Hold the Frame Buffer


Bus Width


Bus Width


Types of Video Memory

  • VRAM (video RAM)

  • MDRAM (multibank DRAM)

  • SGRAM (synchronous graphics RAM)

  • WRAM (Window RAM)

  • 3D RAM


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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