Chapter 10

Supporting I/O Devices

You Will Learn…

How to install peripheral I/O devices How to use ports and expansion slots for add-

on devices About keyboards and how to troubleshoot

them About different types of pointing devices How monitors and video cards relate to the

system, and how to troubleshoot them

Requirements for a New Device

Device driver or BIOS System resources (eg, IRQ, DMA channel, I/O

addresses, upper memory addresses) Application software

Basic Principles of Peripheral Installations

Peripheral is a hardware device controlled by software; install both hardware and software

Software might be of different types; install all levels

More than one peripheral device might attempt to use same computer resources; resolve resource conflicts

Installation Overview

1. Install the device (internal or external)2. Install the device driver3. Install the application software

Installing a Hardware Device

Turn off PC, plug in the device, and reboot If device is PnP, the Add New Hardware

Wizard launches

Installing a Hardware Device

Installing a Hardware Device

Using Ports and Expansion Slots for Add-on Devices

Devices can:• Plug directly into a port (serial, parallel, USB, or

IEEE 1394)• Use an expansion card plugged into an expansion slot

All computers come with:• One or two serial ports• One parallel port• One or more USB ports or an IEEE 1394 port (on newer

computers)

Port Speeds

Using Serial Ports

Transmit data in single bits Identified by counting the pins Sometimes called DB-9 and DB-25 connectors Almost always male Originally intended for input and output devices Can be configured for COM1, COM2, COM3, or

COM4 Conforms to RS-232c standard interface

Serial, Parallel, and Game Ports

Default Port Assignments

Port Assignments

Verifying a Port Is Configured Correctly

Serial Port Specifications

Null Modem Connection

Special cable (null modem cable or modem eliminator) enables data transmission between two DTE devices without the need for modems

Null modem cable has several wires cross-connected to simulate modem connection

Null Modem Cable

Null Modem Cable

Infrared Transceivers

Use resources of the serial port for communication

Create a virtual infrared serial port and virtual infrared parallel port for infrared devices

Common problem: line-of-sight issue• Radio technology (eg, Bluetooth or 802.11b) is

most popular way to connect wireless I/O device

Using Parallel Ports

Transmit data in parallel, eight bits at a time Cable longer than 10 or 15 feet can

compromise data integrity Almost always female Commonly used by printers; also for some

input devices Can be configured as LPT1, LPT2, and LPT3

Types of Parallel Ports

Standard parallel port (SPP)• Data flows in one direction• Comparatively slower

Enhanced Parallel Port (EPP)• Bidirectional

Extended Capabilities Port (ECP)• Bidirectional• Uses a DMA channel

A Standard Parallel Port

Using USB Ports

Expected to ultimately replace serial and parallel ports• Faster• Use higher quality cabling• Easier to manage

Allows for hot-swapping and is hot-pluggable Used by many devices (eg, mice, joysticks,

keyboards, printers)

Using USB Ports

Using USB Ports

Using USB Ports

USB Host Controller

Polls each device, asking if data is ready to be sent or requesting to send data to the device

Manages communication to the CPU for all devices, using only a single IRQ, I/O address range, and DMA channel

Automatically assigns system resources at startup (with the OS)

Requirements for Installing a USB Device

Motherboard or expansion card that provides a USB port

OS that supports USB USB device USB device driver

Installing a USB Device

Using IEEE 1394 Ports

Also called FireWire and i.Link Transmits data serially; faster than USB Supports data speeds as high as 1.2 Gbps Likely to replace SCSI for high-volume, multimedia

external devices Devices can be daisy-chained together and managed

by a host controller using a single set of system resources

Uses isochronous data transfer

Types of IEEE 1394 Ports

IEEE 1394 Ports

Using PCI Expansion Slots

PCI bus is now the standard local I/O bus Devices connected to it can run at one speed

while the CPU runs at a different speed Often used for fast I/O devices (eg, network

cards or SCSI host adapters)

Using PCI Expansion Slots

PCI Bus Master

Manages the PCI bus and expansion slots Assigns IRQ and I/O addresses to PCI

expansion cards PCI bus uses an interim interrupt between the

PCI card and the IRQ line to the CPU

Using PCI Expansion Slots

Using PCI Expansion Slots

Using ISA Expansion Slots

Configuration is not automated ISA bus does not manage system resources ISA device must request system resources at

startup

Keyboards

Traditional straight design or ergonomic design

Two technologies for keys making contact• Foil contact• Metal contact

An Ergonomic Keyboard

Correct Position at the Keyboard

Keyboard Connectors

PS/2 connector (mini-DIN)• Small, round, with six pins

DIN connector• Round with five pins

USB port Wireless connection

Keyboard Connectors

Keyboard Connector Adapter

Keyboard Connectors

Installing a Keyboard

Usually means plugging it in and turning on the PC

System BIOS manages the keyboard, so no keyboard drivers are necessary (except for wireless keyboards)

Troubleshooting Keyboard

A few keys don’t work The keyboard does not work at all Key continues to repeat after being released Keys produce wrong characters Major spills on the keyboard

Pointing Devices

Mouse• Wheel mouse• Optical mouse

Trackball Touch pads

How a Wheel Mouse Works

Mouse Connection Types

Serial mouse Motherboard mouse or PS/2 compatible mouse Bus mouse Using a USB port Using a Y-connection to share a port with a

keyboard Cordless technology

Cleaning the Mouse

Remove cover Clean rollers with cotton swab dipped in small

amount of liquid soap

Manufacturers of Keyboards and Pointing Devices

Troubleshooting a Mouse

Check mouse port connection; check for dust or dirt inside; reboot the PC

Try a new mouse Using Device Manager and Add New Hardware icon

in Control Panel, uninstall then reinstall mouse driver; reboot the PC

Reboot PC and select logged option from startup menu to create Bootlog.txt file; continue boot and check log for errors

Computer Video

Necessary components for video output• Video controller• Monitor

Monitors

Rated by screen size, resolution, refresh rate, and interlace features

Most meet standards for Super VGA (Video Graphics Adapter)

Use either CRT (cathode-ray tube) technology or LCD (liquid crystal display) technology

How a CRT Monitor Works

Choosing the Right Monitor

Monitors

Monitors and ELF (extremely low frequency) emissions

Flat panel monitors• Active-matrix• Dual-scan passive matrix

Layers of an LCD Panel

Installing Dual Monitors

Increases size of Windows desktop

Video Cards

Quality of video subsystem is rated according to how it affects:• Overall system performance• Video quality (eg, resolution and color)• Power-saving features• Ease of use and installation

Features to look for:• The bus it uses• Amount of video RAM it has or can support

Buses Used by Video Cards

VESA (Video Electronics Standards Association) bus

PCI bus AGP bus

VESA Bus

AGP Bus

Graphics Accelerators

Type of video card that has its own processor to boost performance

Features reduce burden on motherboard CPU, eg:• MPEG decoding• 3-D graphics• Dual porting• Color space conversion• Interpolated scaling• EPA Green PC support

Video Memory

VRAM (Video RAM) SGRAM (synchronous graphics RAM) WRAM (window RAM) 3-D RAM

Video Card Manufacturers

Troubleshooting Video Problems

Power light (LED) does not go on; no picture Power LED light is on; no picture on power-up Power on; monitor displays wrong characters Monitor flickers and/or has wavy lines No graphics display or screen goes blank when

loading certain programs

continued…

Troubleshooting Video Problems

Screen goes blank 30 seconds or one minute after keyboard is left untouched

Poor quality color display Picture out of focus or out of adjustment Crackling sound

Video Problems

To configure or change monitor settings and drivers in Windows

To change the video driver configuration Returning to standard VGA settings

Changing the Video Driver Configuration

Chapter Summary

Installing and supporting I/O devices Procedures and guidelines common to most

installations How to use serial, parallel, UB, and IEEE 1394

ports, and expansions slots Essential I/O devices for a PC: keyboard,

mouse, and video