supporting io devices

7/31/2019 Supporting Io Devices

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Supporting I/O

Devices


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Basic Principles of PeripheralInstallations

Both hardware and software must beinstalled (hardware is controlled by software)

Install all levels of software

Device driver must be written specifically forthe OS

More than one peripheral device might

attempt to use same resources

Update drivers, the firmware, or both


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Installation Overview

1. Install the device (internal or external)

2. Install the device driver

3. Install the application software


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Ports


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Using Ports and Expansion Slots forAdd-on Device

Ports Serial

Parallel

USB

IEEE 1394

SCSI

Expansion slots


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Port Speeds


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Using Serial Ports

Transmit data in single bits (serially)

Nine or 25 pins

Almost always male

Originally intended for input and output

devices

Configured as COM1, COM2, COM3, or

COM4


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Using Serial Ports (continued)

Port assignments are made in CMOS setup

Conform to standard interface called RS-

232c

Data Terminal Equipment (DTE) and Data

Communications Equipment (DCE)

designations


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Port Comparison


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Default Port Assignments


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Null Modem Connection

Enables data transmission between two DTEdevices without the need for modems

Special cable (null modem cable) has several

wires cross-connected to simulate modem

connection


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Pin Connections for a 25-PinNull Modem Cable

Wi C ti 25 Pi


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Wire Connections on a 25-PinNull Modem Cable


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Infrared Transceivers

Use resources of a serial port for

communication

Create a virtual infrared serial port and virtual

infrared port for infrared devices

UART logic on the motherboard controlsserial ports on the board

Line-of-sight issue


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Using Parallel Ports

Transmit data in parallel, eight bits at a time

Almost always female

Originally intended for printers

Can be configured as LPT1, LPT2, or LPT3

Port assignments are made in CMOS setup Avoid using a cable longer than 15 feet to

ensure data integrity


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Types of Parallel Ports

Standard parallel port (SPP)

Allows data to flow in only one direction

Slowest of the three types

Enhanced Parallel Port (EPP)

Bi-directional

Extended Capabilities Port (ECP) Bi-directional

Uses the DMA channel


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A Standard Parallel Port


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Using USB Ports

Effortless installation of slow peripheral

devices

Much faster than regular serial ports; usehigher-quality cabling

Easier to manage; eliminate need to

manually resolve resource conflicts

Likely to replace serial and parallel ports


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Using USB Ports (continued)

Allow for hot-swapping; are hot-pluggable

Most current motherboards have one to fourUSB ports

Managed by a USB host controller

As many as 127 USB devices can be daisy-

chained together using USB devices


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USB Ports


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USB Host Controller

Requirements for Preparing to


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Requirements for Preparing toInstall a USB Device

Motherboard or expansion card that provides

a USB port

OS that supports USB

USB device

USB device driver


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Using IEEE 1394 Ports

Transmit data serially; faster than USB

Likely to replace SCSI for high-volume, multimedia external

devices

Provide either a 4-pin or 6-pin connector Hot-pluggable

Can be daisy-chained together and managed by a host

controller using one set of system resources

Use isochronous data transfer

Isochronous transfers involve large streams of data. This format is used to move

continuous, real-time data streams such as voice or video. Data delivery rates are

predetermined and correspond to the sampling rate o the device.


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IEEE 1394 Port Standards

IEEE 1394A

Supports data speeds up to 1.2 Gbps

Allows for cable lengths up to 15 feet

IEEE 1394B

Supports speeds up to 3.2 Gbps

Allows for cable length up to 328 feet


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IEEE 1394 Cable Connections


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Using IEEE 1394 Ports


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Keyboards

Traditional straight design or ergonomicdesign

Two technologies for keys making contact

Foil contact

Metal contact

Installing keyboards


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Keyboard Connectors

PS/2 connector (or mini-DIN)

Small, round, with six pins

DIN (Deutsche Industrie Norm) connector

Round with five pins

USB port

Wireless connection

Requires a driver


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Keyboard Connectors (continued)


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Pinouts for Keyboard Connectors


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Pinouts for Keyboard Connectors

You'll notice a few things about the table. First, there

are only four actual signals used in the standard

keyboard interface; the extra pins on both types ofconnector are not used

(This mismatch means that the connectors were

chosen either from existing designs to savedevelopment costs, or that room was left for future

expansion that was never used. Both occur commonly

in the PC industry.)


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A Keyboard Adapter

Since the signals are the same for the two types of connector--they just use different

pins. This means that simple mechanical adapters can be made to convert between

the two. These adapters let a keyboard that terminates in a large connector work on a

system that requires a small connector, and vice-versa.


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Troubleshooting Keyboards

A few keys dont work

Keyboard does not work at all

Key continues to repeat after being

released

Keys produce the wrong characters

Major spills on the keyboard


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Pointing Devices


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How a Wheel Mouse Works

How a Mouse Connects


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How a Mouse Connectsto the Computer

Dedicated round mouse port (motherboard mouseor PS/2-compatible mouse)

Mouse bus card (bus mouse)

Serial port (serial mouse) USB port

Y-connection with the keyboard

Cordless technology


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Pointing Devices

Touch screens

Other pointing devices

Trackballs

Touch pads


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Troubleshooting a Mouse

Check mouse port connection

Check for dust or dirt; reboot PC

Try new mouse

Uninstall and reinstall mouse driver; reboot PC

Reboot PC and select logged option from startup menu to createBootlog.exe file

Continue to boot and check log for errors


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Other Devices

Scanners Web Cameras

Biometric Devices

Bar Code Readers Touch Screens

supporting io devices

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