Download device special files

Guide to Operating Systems,
4th ed.
Chapter 6: Configuring Input and Output
Devices
Objectives
• Understand how operating systems interface with
input and output devices
• Explain the need for device drivers and install
devices and drivers
• Describe popular input device technologies
• Discuss the types of printers and install printers
• Explain display adapter technologies
• Install circuit boards for new devices
• Explain the use of sound cards and other output
devices
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2
Operating Systems and Devices: An
Overview
• A primary function of any OS is to provide basic I/O
support for application software
– To translate requests from software into commands that the
hardware can understand and carry out
• The OS must:
– Handle input from the keyboard, mouse, and other input
devices.
– Handle output to the screen, printer, and other output devices.
– Control information storage and retrieval using various types of
disk and optical drives.
– Support communications with remote computers, such as
through a network.
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Operating Systems and Devices: An
Overview
• There are two ways an OS accomplishes these
tasks:
– Through software(device drivers)
– Through hardware (controllers and adapter boards) controlled
by the OS
• Device drivers perform the actual communication
between the physical device and the OS
• Adapters are the interface between hardware
components (such as display adapters to produce
video).
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4
Operating Systems and Devices: An
Overview
• The configuration of device drivers and adapters
varies from OS to OS, but they function the same
way in each OS
• Setting up or installing input, output, or storage
devices involves three general steps:
– Install any software drivers that are required
– Connect the input, output, or storage device
– Turn on the device and follow any configuration instructions
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Using Device Drivers
• A device driver is software that enables the OS and
application software to access specific computer
hardware.
• The OS provides basic I/O support for devices but
it doesn’t support specific features of each device
– For specific features to be supported and work properly, a
device driver for the device is needed.
• If all computer OS vendors attempted to
incorporate code for all of the possible devices, the
OS kernel would be huge and probably slow.
– Also, the OS kernel would have to be updated each time a new
device came on the market.
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Using Device Drivers
• Advantages of using device drivers:
– Only essential code is necessary to build into the OS kernel for
maximum performance
– Use of specific devices does not have to be linked to a single
OS
– The number of I/O devices can expand to offer the computer
user a broad range of device selections and features
– New devices can come on the market without requiring
extensive updates to OSs
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Using Device Drivers
• You should use the manufacturer’s driver instead of the
one supplied with your OS
– Using the driver shipped with your device gives you a better chance of
having the latest version designed for your specific hardware
• The procedure to install drivers varies with the source
of the driver and the OS you are using.
• If you download a new driver from a manufacturer’s
Web site, you may have to uncompress it
– Microsoft includes built-in zip support (starting in late 90’s)
– Some files may be supplied in self-extraction format (executable file
that usually uses an .exe file extension)
– If the file includes a .zip extension, you’ll need a program like PKZIP or
WinZip to expand the file before installing
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Using Device Drivers
– Mac OS X since version 10.3 Tiger has built-in zip support
– UNIX/Linux users may retrieve drivers in a tar format
• Tar files also are archives that group multiple files into a single
distribution file.
• Tar doesn’t compress the files; it merely groups files to make it
easier to copy and distribute multiple files together.
• Once the driver is located, you generally have 3
options for install:
– Use your OS’s install utility
– Plug and Play (PnP) feature
– The install utility provided by the hardware manufacturer
• Procedures differ among different OSs and with
different equipment.
– General process is very similar
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Using Device Drivers
• Manufacturer Driver Installation – most come with
an install utility that makes driver installation fully
automatic
– If problems occur, go to manufacturer’s Web site or looks for a
.txt file on the install disk for more information
• Windows XP (and later versions) Driver Installation
– Easiest way to install a driver is to use the PnP capability to
automatically detect new hardware and install drivers.
– Also can use the Add Hardware Wizard in Windows
– A third way is to use a specialized Control Panel icon.
– A final way is to use Device Manager – install a new driver or
update an existing one
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Using Device Drivers
• Using PnP to Install a Device and Driver
–
–
–
–
Install any software drivers that are required
Connect the printer to the computer
Plug the printer into a power outlet and turn it on
Follow any configuration instructions
• When the printer is turned on, the OS recognizes
that a new piece of hardware is attached and tries
to locate the drivers for it.
• Windows may try to find the built-in driver for the
device on the Windows distribution disk or
DVD/CD-ROM
• You can insert the manufacturer’s DVD/CD-ROM
into the appropriate drive when the OS asks for it
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Using Device Drivers
• Using a Windows Wizard to Install a Device/Driver
– Use the Add Hardware Wizard if:
• Windows doesn’t recognize newly installed hardware
• Want to conduct an installation manually
• To start automatic procedures to detect a hardware device
– Starting the Add Hardware Wizard varies from OS to OS (see
examples of how to start on page 310)
– When using the Wizard, the drivers may not be the most
current
• It is recommended to use the installation CD from the device
manufacturer (if available) to ensure the latest drivers are used
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Using Device Drivers
• Using Control Panel to Install a Device/Driver
– Many devices can be configured through Control Panel
– Examples are: monitor, game controllers, keyboard, mouse,
network interfaces, printers and faxes, scanners, etc…
– Double-click the icon and look for configuration options
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Using Device Drivers
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Using Device Drivers
• Using Device Manager to Install or Update a Driver
– Also use Device Manager to:
• Determine the location of device driver files
• Check to make sure a device is working properly
• Determine if there is a resource conflict for a device
– The Device Manager places a question mark on the device if there is
a problem with the installation
– The driver is not installed.
• When you access a device through Device Manager that has a
utility setup, the utility checks to verify that the device is working
properly.
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Using Device Drivers
• Using Device Manager to Install or Update a Driver
– A device uses the computer’s resources to enable it to function
and communicate with the computer.
– A computer’s resources include the interrupt request (IRQ)
line and one or more I/O address ranges.
• The IRQ line is a channel within the computer that is used for
communication with the central processing unit (CPU).
• The I/O address range is memory reserved for use by a particular
device.
– If more than one device is assigned the same IRQ line or I/O address
range, then those devices become unstable or may not work
together.
• device Manager not only shows the IRQ line and I/O address for a
device, but also lets you know if it detects a conflict.
– Hands-On Project 6-2 gives you the opportunity to use Device
Manager
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Using Device Drivers
• When a new I/O device is installed under Windows,
you have the option to make sure the driver has
been verified by Microsoft
• When it has been verified a unique digital signature
is incorporated into that driver (a process called
driver signing)
• Using driver signing helps to ensure that the driver
works properly with the device and in conjunction
with other devices
• Hands-On Project 6-3 shows you how to configure
driver signing in Windows XP and Server 2003/R2
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Using Device Drivers
• When you configure driver signing, you configure it
to apply to all new software installations, as well as
device drivers.
– Many critical OS files are also signed.
• Each time you install a word processor or
spreadsheet application, there is a risk that an
important OS file may be overwritten by an
unsigned file.
• If you have selected the Block option, this means
that drivers and OS files cannot be modified or
overwritten by files that do not have the appropriate
digital signature.
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UNIX/Linux Driver Installation
• Concept of drivers is a little different in UNIX/Linux
• Central portion of the OS, the kernel, is where most
of the device drivers are loaded
• Drivers are either in the form of:
– Kernel modules – pieces of code that must be linked into the
kernel
– Loadable modules – pieces of code that are not linked into the
kernel, but are loaded when the OS is started
• Device support in most
• Oss
– Device manufacturers often provide drivers for special
hardware, which are linked or loaded into the kernel.
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UNIX/Linux Driver Installation
• UNIX/Linux devices are managed through the use of
device special files (contain information about I/O
devices used by the OS kernel when a device is
accessed).
• Three types of device special files:
– Block special files – used to manage random access devices that
involve handling blocks of data (hard drives, DVD/CD-ROM drives)
– Character special files – handle byte-by-byte streams of data (USB
connections such as mice, keyboards, printers, etc…)
– Named pipes – handling internal communications, such as redirecting
file output to a monitor
• Device special files are usually stored in the /dev
directory
– To view, use the ls command to see all of the files in the /dev folder
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UNIX/Linux Driver Installation
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UNIX/Linux Driver Installation
• If you need to create a device special file for a new
device, you can do so by using the mknod command:
–
–
–
–
Log in with superuser permissions.
Access a terminal window or the command prompt.
Type cd /dev and press Enter to switch to the /dev folder.
Use the mknod command plus the device special file name
• Device special files are usually stored in the /dev
directory
– To view, use the ls command to see all of the files in the /dev folder
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Mac OS X Driver Installation
• Mac OS X systems come with device drivers for
most hardware that connects to those systems.
• When you obtain new hardware, follow these
general steps:
– Make sure that you have an installation DVD/CD-ROM from the
manufacturer for that hardware.
– Shut down the OS and turn off the computer
– Attach the new hardware
– Restart the computer and OS
– Insert the DVD/CD-ROM for the hardware
– Run the installer program on the DVD/CD-ROM for that
hardware
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Standard Input Devices
• Mouse and Keyboard Drivers:
– Highly standardized across OSs, it is unlikely you will need to
setup these devices (drivers are usually standard).
– These drivers are standard and, in most cases, included as part
of the OS.
• Wireless mice and keyboards require batteries to
operate, along with a USB receiver (usually shared
by both mouse and keyboard)
– May come with drivers and additional software on DVD/CDROM
• Some OSs include keyboard and mouse
configuration utilities
– Example – you can set the double-click speed of a mouse
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Standard Input Devices
Changing mouse preference in Snow Leopard
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Standard Input Devices
• Touch Input Drivers – most often, drivers are
included in the OS or preloaded by the computer
manufacturer
– Touch Screen is controlled by using your fingers
– Multi-touch technology allows you to use multiple fingers to
resize a windows, scroll through documents, or page forward or
back in your Web browser.
• To use multi-touch, you need a laptop or monitor
equipped with multi-touch technology.
• Windows 7 and Linux/Fedora support multi-touch
capabilities.
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Standard Input Devices
• Apple will most likely be incorporating the touch
technology already used in the iPad and iPhone in
the next version of Mac OS X.
• Touch pad is an example of touch input.
– Usually found below the keyboard on laptops.
– A surface that converts finger motion and position to a point on
your screen.
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Standard Input Devices
Touchpad settings
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Other Input Devices
• Digital Pads – A different kind of mouse.
– Used to draw pictures, sign your name, color a detailed graphic
image, and other tasks that require a high degree of manual
dexterity.
– Uses a USB port and requires special drivers/installation
– Can range from standard simple hardware to specialty devices
that include LCD panels that mirror your computer’s video
display.
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Other Input Devices
• Scanners – scans text and images to be
manipulated by software on your computer.
– Once in the computer, the digital image from the scanner can
be saved in a variety of graphics image formats, edited, merged
with other images or text, transmitted over the Internet or other
network connection, and printed.
– Instead of scanning text into a digital graphic image, which
does not allow for text manipulation, imaging software scans
each character on the page into a distinct image.
– May also be used with optical character recognition (OCR)
software.
– If you’re using a USB scanner with Windows, installation and
configuration should be automatic through PnP.
– To get the best performance, install drivers that shipped with
scanner instead of the driver in Windows.
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Other Input Devices
• Joysticks, Game Pads, and Other Controllers
– Joystick is more like a mouse instead of a digital pad
• Uses a mechanical or optical device to rotate one or more
potentiometers.
• Changing resistance tells the joystick driver what value to feed to
the OS and any associated application software.
• Offers more control than a mouse when it comes to detailed
movements of graphical screen objects.
• Can be used for any application input task, given the proper driver.
– Specialized joysticks: flight yoke systems, 3D joysticks, attack
joysticks.
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Other Input Devices
• Game Pads – designed for interaction with games
and include multiple buttons, wheels or balls to
effect movement of a variety of on-screen objects.
• Sends standard signals to the USB port where the OS takes data
and passes it off to an application program or customer driver for
interpretation.
• Some are wireless and programmable and some have LCD
displays.
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Other Input Devices
• Digital Sound Input – today’s computer is supplied
with some kind of digital sound card for sound input
and output.
– May be built into the motherboard or a separate card
– Can connect a microphone to a USB port and record voice mail
that you can include with electronic mail or for narration of slide
presentations.
– Along with your webcam, you can use the microphone to make
audio and video calls with Skype and VoIP (Voice over Internet
Protocol) applications
• Skype is application software that allows you to make calls with or
without video over the Internet, instant messaging and video
conferencing.
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Other Input Devices
• Digital Sound Input – today’s computer is supplied
with some kind of digital sound card for sound input
and output.
– Can download custom sounds or music from Internet sites for
use with software applications
– Most digital audio interfaces plug into the USB port.
– If you need to transfer audio into multiple computers, the USB
interface as a good choice because USB is self-configuring and
most USB devices are external to the computer.
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Other Input Devices
• Digital Picture and Video Input/Output
– Works similarly to digital audio I/O
– Need a digital I/O interface and drivers to allow your OS to use
the USB device
– You import the digital images into whatever application
software you are using for picture or video editing.
– In some cases, use a utility supplied by the manufacturer to
import digital images
– Some manufacturers include the ability to link their hardware
drivers directly into editing software so you can import and
export digital files from an external camera and edit them from
the same application.
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Other Input Devices
• 1394 Technology – IEEE 1394 is the original
specification for a high-speed digital interface that
supports data rates at 100, 200, or 400 Mbps
– Currently targeted at multimedia peripherals
– The newer 1394a and1394b standards supports 800 Mbps, 1.6
and 3.2 Gbps
• 1394b enables data transfer over twisted-pair and fiber-optic
cable.
• FireWire – an IEEE 1394 implementation for bus
communications, is used by Apple Computer and
Texas Instruments.
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Printers
• Printer types:
– Ink-jet printers – create characters by squirting tiny drops of
ink directly onto the page.
• Models that deliver color and high resolution are used for proofing
by graphics designers and printers, as well as home and office
users.
– Laser printers – use an imaging technology similar to copiers
to produce computer output.
• The most popular printer design for business text and graphics.
• Typical laser printer contains its own CPU and memory because
printed pages are first produced electronically within the printer.
– Multifunction printers – combine color ink-jet or laser printing,
scanning, copying, and faxing into one physical device.
– Good for locations that do not have a lot of desktop space.
– If it breaks, you lose all functions.
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Printers
• Printer types:
– Other types available:
• 3D printers – Use an additive process to create one layer at a time
of the object.
• Label printers – Only produce labels.
• Dot-matrix (Impact printer) – Produce characters by slamming a
group of wires (dots) from a rectangular grid onto a ribbon and
then onto paper to produce characters.
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Printers
• Printer types:
– Other types available:
• Line printers – Used on older mainframes, print an entire
line at a time rather than a character at a time.
• Portable printers – Lightweight and can be carried with
you when you travel
– Usually ink-jet printers and may come with a battery.
• Thermal-wax transfer printers – Exist in two basic
designs:
– One uses rolls of plastic film coated with colored wax, which is
melted onto the pages, one primary color at a time
– A second type (phase change) melts wax stored in individual
colored sticks and sprays the molten colored wax onto the
page.
» Generally produce very high-quality
» Relatively slow
» Require special paper.
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Printers
• Printer Types:
– Other types available:
• Dye sublimation – Don’t melt pigments and spray them onto the
paper.
• They vaporize them.
• This colored gas penetrates the surface of the paper to create an
image on the page.
• Produces high-quality output.
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Printers
• Printer Connections
– Most new printers come standard with a USB port
– Many printers support wireless printing
– Some printers have a direct network connection option that lets
you place the printer on a LAN
• If a printer does not include this, you can purchase a network
printer interface from a third party
– More efficient to use a direct network-attached printer rather
than a printer attached to a computer and configured for
sharing on a network
• Network interface is always on, making the printer always
available to network users
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Installing Printers
• Installing Windows Printers – usually installed by
connecting the printer to the computer and letting
PnP initiate the installation
– Can also connect the printer and use Add Hardware Wizard
– Best approach is to insert the DVD/CD-ROM that came with the
printer and follow the instructions
– If you need to perform a manual installation or to initiate
automatic detection and setup, use the Add a Printer option
through Control Panel
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Installing Printers
• Installing UNIX/Linux Printers
– When a print job is sent from an application, a print queue
(spooler) temporarily stores the print job until it is sent to the
printer
• Sections of computer memory and hard disk storage.
– In order to configure a printer, you must first define the printer
parameters and the print queue
• All definitions are kept in the file /etc/printcap
• File is in ASCII text and can be edited by hand – there are utilities
that make the job easier (utilities vary by version)
– Red Hat Enterprise Linux uses a printer configuration utility
called printtool
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Installing Printers
Using the printtool command in Red Hat Enterprise
Linux
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Installing Printers
• Installing Mac OS X Printers
– Most printer drivers are already installed when you install the
OS
– If not, use the Printer Setup Utility and the DVD/CD-ROM that
came with the new printer
– You can configure the following types of printers:
• LPR – for connecting to a shared network printer that uses the
traditional UNIX-based LPR configuration
• IP – for printing on a network through TCP/IP
• FireWire – for connecting through an IEEE 1394 interface
• USB – most typical type of printer connection
• FAXstf – for sending a print file to a fax machine
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Display Adapters
• Display adapters have evolved through many bus
standards
– The general acceptance of first, the Peripheral Component
Interconnect (PCI) bus, then the Accelerated Graphics Port
(AGP) bus, and finally the Peripheral Component Interconnect
Express (PCIe) bus standard has enabled adapter
manufacturers to supply one hardware product to a variety of
hardware platforms.
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Display Adapters
• The display adapter is part of a standard computer
package
– Basic display consists of a number of pixels (small dot of light)
both horizontally and vertically
– The more pixels on the screen, the larger the monitor needs to
be
• 19” monitor is recommended for 1280X1024 resolution
• 21” monitor is recommended for 1600X1200 resolution
• Major considerations in choosing an adapter are:
–
–
–
–
Resolution capabilities
Amount of memory included onboard the adapter
Type of video processor (optional, used to speed things up)
Cost
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Display Adapters
• No matter what computer platform you are using,
the basic display consists of a number of pixels
horizontally and a number of pixels vertically.
– A pixel is a picture element (a small dot of light) that represents
one small portion of your overall screen display.
• As you display more pixels on the screen, you’ll
need a larger monitor to comfortably read the
displayed data.
– The higher resolution displays can present more data at a time
on the screen, but this data is presented in a smaller format.
• A 1024 X 768 display is best on a 17” monitor.
• A 1280 X 1024 display is best on a 19” monitor.
• A 1600 X 1200 display is best on a 21” monitor.
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Display Adapters
• Bit density – how many pixels (dots) can be
shown in an inch of the display
– Pixels per inch (ppi) - Monitor
– Dots per inch (dpi) – Printer
– The more ppi/dpi, the higher the resolution. The higher the
resolution, the clearer the picture.
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Display Adapters
• Most computers ship with a flat panel monitor,
which takes up less space, uses less energy,
produces less heat and can provide a flicker-free
image.
• Digital Visual Interface (DVI) – developed as a
very high visual quality standard for flat panel LCD
and digital projectors.
– 1920 X 1200 is the standard for a single cable.
– A dual cable can display 3840 X 2400 at 33 Hz.
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Display Adapters
• DVI is mostly compatible with the High-Definition
Multimedia Interface (HDMI)
– A way to connect digital audio/video devices in televisions and
computers.
• Display-Port – A digital interface standard that is
projected to replace DVI and HDMI for computers.
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Installing Display Adapters
• The majority of display adapters are supplied as
cards that plug into the PCIe slot on the
motherboard.
• The PCIe bus has become a popular standard
among computer hardware manufacturers,
including Intel-based computers, Macintosh
computers, and workstations designed for UNIX,
Oracle and other systems.
• As with printers and other hardware, display
adapters are installed in two phases:
– Hardware
– software
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Sound Cards
• Today, most computers include high-end audio
support.
• Multimedia, sound output and even quality
recording capabilities have become important to a
broader range of users.
• The sound card comes preinstalled, and the OS
includes integral support for sound input and output
on newer computers.
– There are drivers for individual pieces of sound hardware that
must be installed.
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Sound Cards
• Two types of sound devices :
– Bus cards (installed in a bus slot similar to a display adapter)
– Hardware integrated with the motherboard (onboard).
• Increasingly you will see sound cards built into the
motherboard.
– This provides the easiest installation because the hardware is
always there, and all you might need to do is install or configure
drivers.
– The downside to motherboard sound hardware, is that it may
be harder to update or change the hardware.
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Other Output Devices
• Digital video
– A popular consumer and professional computer-based feature.
– Adapter cards let you capture and output digital video to a
camera or DVR are available, coupled with capable , low-cost
video editing software.
• Multiport sound cards
– Available that permit a computer to serve as a fully digital,
multichannel recorder for sound studio applications.
• Most specialty output devices have some software
required to make everything work properly
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Installing Circuit Boards
• The biggest enemy of the devices supplied on
circuit boards or cards is static.
– High-voltage, low current charges that can exist between any
two devices, including human bodies.
• To avoid damage during installation:
– Leave the card inside its protective cover until you are ready to
install it.
– Disconnect all power to the computer.
– Prepare the computer by removing the case and any slot
covers for the slots you will use.
– Position the card inside its cover, near the computer.
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Installing Circuit Boards
• To avoid damage during installation (contid):
– Touch a grounded part of the computer (power supply).
• Without removing your hand from the computer, open the bag and
remove the card you are about to install.
• Insert the card into the slot and press it firmly into
place.
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Installing Circuit Boards
Typical card being placed in a computer
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Chapter Summary
• An OS handles input and output device communications through
device drivers (software) and hardware such as adapter boards
• Device drivers are often provided with an OS, but the most up-todate device drivers come directly form each device manufacturer
• Manufacturer device and device driver installations typically are
performed from a manufacturer’s DVD/CD-ROM. Current drivers
can also be downloaded from the manufacturer’s Web site
• Installing devices and drivers in Windows can be done using PnP,
the Add Hardware Wizard, Control Panel options, and Device
Manager
• UNIX/Linux systems use device special files for managing input
and output devices
• For Mac OS X devices, most drivers come with the OS or can be
installed from the DVD/CD-ROM that came with the device
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Chapter Summary
• Common input devices include a mouse, keyboard, touch
input, digital pad, scanner, joystick, game pad, digital sound
devices, digital picture devices, and devices that use 1394
technology
• Printers are common output devices
• Most OSs include tools for installing printers, such as Add
Printer Wizard in Windows, printtool in Fedora Linux, and the
Printer Setup Utility in Mac OS X
• Besides printers, other examples of common output devices
include display adapters and sound cards
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