Slide 1 Computer Confluence 7/e Chapter 3 Hardware Basics: Peripherals © 2006 Prentice-Hall, Inc

Slide 1

Computer Confluence 7/e

Chapter 3

Hardware Basics: Peripherals

© 2006 Prentice-Hall, Inc.

Slide 2

Computer Confluence 7/e Chapter 3Objectives

Input devices and their roles in getting different types of information into the computer

Output devices and the ways they make computers more useful

The functionality of different types of storage devices

The ways the components of a computer system fit together


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Computer Confluence 7/e Chapter 3

Input: From Person to Processor

KeyboardThe most familiar input

deviceUsed to enter letters, numbers

and special characters


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Standard keyboard Ergonomic keyboards

To address possible medical problems Place the keys at an angels that are

easier on your arms and hands.Wireless keyboardFolding keyboards

Used with palm-sized computersOne-handed keyboards Keyboards printed on membranes that can be rolled or folded like paper.


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this standard-size fabric keyboard rolls up into a lightweight, compact package that can be tucked into a pocket, or briefcase.

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Pointing Devices Mouse

Portable computers :Touchpad (track pad)Pointing stick Trackball

Other pointing devices :Joystick Graphics tablet

stylusTouch screen


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Variants of the Mouse

• Trackballs– Upside down mouse– Hand rests on the ball– User moves the ball– Uses little desk space

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Variants of the Mouse

• Track pads– Stationary pointing

device– Small plastic rectangle– Finger moves across

the pad– Pointer moves with the

pointer– Popular on laptops

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Variants of the MouseTrack point

– Little joystick on the keyboard– Move pointer by moving the joystick

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Devices for the Hand

• Pen based input– Tablet PCs, PDA– Pen used to

write data– Pen used as

a pointer– Handwriting

recognition

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Devices for the hand

• Touch screens– Sensors determine

where finger points– Usually presents a

menu to users– ATM’s, Malls,

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Reading ToolsReads marks

representing codes specifically designed

for computer input


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Optical-mark readers:

use reflected light to determine the location of pencil marks on standardized test answer sheets and similar forms.


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Input: From Person to Processor Magnetic-ink character readers : read those odd-shaped

numbers printed with magnetic ink on the checks. Bar-code readers use light to read universal product code (UPC). They are

attached to point of sale terminals (POS). These terminals send the scanned information to a mainframe computer => item’s price, calculate total.

Radio Frequency Identification Readers : use radio waves to communicate with Radio Frequency

Identification (RFID) tags. When energized by a nearby RFID reader, an RFID tag broadcasts its unique identification number to the reader. which digitizes the information for input into a computer.

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An RFID tag used for

electronic toll collection

• RFID tags used in libraries: square book tag, round CD/DVD tag and rectangular VHS tag.

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Input: From Person to ProcessorBecause test forms, magnetic ink character, bar codes,

and RFID tags were designed to be read by computers, the devices that read them are extremely accurate.

Reading text from books, magazines, and other printed document is more challenging because of the great variety of printed text.

Optical character recognition (OCR) is the technology of recognizing individual characters on a printed page, so they can be stored and edited as text.

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Input: From Person to ProcessorBefore a computer can recognize handwriting or

printed text, it must first create a digital image of the page that it can store in memory.=>scanner.

A scanner doesn’t actually read or recognize letters and numbers on a page- it just makes a digital “ picture” of the page available to the computer.

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Pen scanners :

looks like highlighters.Wireless scanners that can

perform character recognition.

pen-based computers such as the Tablet PC can work without a

keyboard accept input from a stylus handwritten recognition

software to translate the user’s handwritten forms into ASCII characters.

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Personal digital assistants (PDAs): are handheld pen

computers that serve as organizers, notebooks, communication devices, ….

Smart whiteboard: serve as an input device

for a PC. board is stored as a

digital image on the computer’s disk.

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Digitizing devices

• Before a computer can recognize hand-written or printed text, a scanner or other input device must digitize the information- convert it into a digital form-.

• A scanner is an input device that can create a digital representation of a printed image.

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Digitizing the Real World

Scanners capture and digitize printed images

Flatbed Slide scanner : scan only slides and negatives.Drum : larger and more expensive.Sheet-fed : small, portable, and inexpensive.


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Drum scanner

Sheet fed scanner

Slide scanner

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Digital cameraSnapshots captured as

digital imagesDigital images stored as

bit patterns on disks or other digital storage media


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Input: From Person to ProcessorVideo digitizer

Capture input from a:Video cameraVideo cassette recorder or television

Convert it to a digital signalStored in memory and displayed on computer screens

Digital video camera can send video signals directly into a computer without a video digitizer.

Videoconferencing People in diverse locations can see and hear each other

Used to conduct long-distance meetings Video images transmitted through networks


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Input: From Person to ProcessorAudio digitizers

Digitize sounds from Microphones Other audio input devices

Digital signals can be Stored Further processed with specialized

software A digital signal processing chip

compresses the stream of bits before it is transmitted to the CPU


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Audiovisual Input Devices

• Microphones– Used to record speech– Speech recognition

• “Understands” human speech• Allows dictation or control of computer• Matches spoken sound to known phonemes• Enters best match into document

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Speech recognition software Converts voice data into words that

can be edited and printed


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Sensors Designed to monitor physical conditions

Temperature, humidity, pressure Provide data used in:

Robotics Environmental climate control Weather forecasting Medical monitoring Biofeedback Scientific research


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Output: From Pulses to PeopleScreen Output

A monitor or video display terminal (VDT) displays characters, graphics, photographic images, animation and video

Video adapter —connects the monitor to the computer a circuit board installed in a slot inside the system unit

VRAM or video memory —a special portion of RAM to hold video images the amount of VRAM determines the max. resolution and color depth.the more video memory, the more picture detail is displayed.


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Output: From Pulses to PeopleMonitor size: Measured as a diagonal line across the

screenResolution: The number of pixels displayed on the screen

Pixels (or picture elements): tiny dots that compose a pictureThe higher the resolution, the closer together the dots and the clearer the image.

Image quality is affected by resolution and color depth (or bit depth)

Color depth refers to the number of different colors a monitor displays at one time


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Monitors

• Categorized by color output– Monochrome

• One color with black background

– Grayscale• black, white, and Varying degrees of gray

– Color• Display 4 to 16 million colors

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Output: From Pulses to PeopleMonitor classes

CRTs (cathode-ray tubes)

LCDs (liquid crystal displays) are now more

popular Overhead projection panels Video projectors Portable computers


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Monitors

• Cathode Ray Tube (CRT)– Electrons fired from the back– Electrons excite phosphor to glow– Phosphor is arranged in dots called pixels

• CRT drawbacks– Very large – Very heavy– Use a lot of electricity

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Flat-panel Monitors• Liquid Crystal Display (LCD)

– Commonly found on laptops– Desktop versions exist– Solve the problems of CRT– Fluorescent lights provide illumination

• Electro-luminescent displays (ELD)– Similar to LCD– Uses phosphor to produce light

• Plasma monitor– Gas is excited to produce light

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Output: From Pulses to People

Paper OutputPrinters produce paper output or hard copy Two basic groups of printers:

Impact printers nonimpact printers


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Commonly Used Printers• Impact printers

Line printers Dot-matrix printers

– Generate output by striking the paper, ribbon, and print hammer together.

– Uses an inked ribbon

• Non-impact printers– Use methods other than force– Tend to be quiet and fast

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Commonly Used Printers

• Line printers

- Impact printer

- speedy but noisy

- limited to printing characters.

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Commonly Used Printers

• Dot matrix printers– Impact printer– Used to print to multi-sheet pages– Print head strikes inked ribbon

– Speed measured in characters per second

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Dot Matrix Print Head

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Output: From Pulses to PeopleNon-impact printersLaser printers

Laser beam reflected off a rotating drum to create patterns of electrical charges

Faster and more expensive than dot matrix printer

Produce High-resolution output Color or black and white Print process

– Laser draws text on page– Toner sticks to text– Toner melted to page

Speed measured in pages per minute Quality expressed as dots per inch

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Inkjet printers Sprays ink onto paper to produce

printed text and graphic images Prints fewer pages/minute than

laser printer High-quality color costing less than

laser printer Speed measured in pages per

minute Quality expressed as dots per inch

Non-impact printer

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Dots Per Inch

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High-Quality Printers

• Photo printers– Produces film quality pictures– Prints very slow– Prints a variety of sizes

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Multifunction printer or MFP combines a scanner, printer and a fax modemPlotter: an automated drawing tool that can produce large, finely scaled engineering blueprints and maps


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Output: From Pulses to PeopleFax Machines and Fax ModemsFacsimile (fax) machine

Sending: fax machine scans each page as an image, converts the image into a series of electronic pulses,sends those signals over phone lines to another fax.

Receiving: fax machine uses the signals to reconstruct the image andprint black-and-white facsimiles or copies of the originals


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Fax Machines and Fax Modems

Fax modem: directly from PC to fax machine via modem & phone

line translate the document into signals that can be sent

over phone wires.Decoded by the receiving fax machine. (remote printer) receive transmission from fax machine (remote

scanner)

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Output You Can HearSound card

Enables the PC to:Accept microphone inputPlay music and other sound through speakers or headphonesProcess sound in a variety of ways

Synthesizers Specialized circuitry used to produce music, noise electronically.


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Controlling Other Machines

Output devices take bit patterns and turn them into non-digital movements

Robot armsTelephone switchboardsTransportation devicesAutomated factory equipmentSpacecraftForce feedback joystick


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Output: From Pulses to PeopleRules of Thumb: Ergonomics and

Health

Choose equipment that’s ergonomically designedCreate a healthy workspaceBuild flexibility into your work environmentRest your eyesStretch to loosen tight musclesListen to your bodySeek help when you need it


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Describing Storage Devices

• Store data when computer is off

• Two processes– Writing data– Reading data

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Describing Storage Devices

• Storage terms– Media is the material storing data– Storage devices manage the media– Magnetic devices use a magnet– Optical devices use lasers– Solid-state devices have physical switches

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Magnetic Storage Devices

• Most common form of storage

• Hard drives, floppy drives, tape

• All magnetic drives work the same

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Magnetic Storage DevicesFloppy DiskFloppy Disk

Hard DiskHard Disk

TapeTape

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Storage Devices: Input Meets Output

Magnetic TapeCan store large amounts of information in a small space at a relatively low costLimitation: slow sequential data access : retrieve information by zipping through it in the order in which it was recorded. Used mainly for backup purposes


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Storage Devices: Input Meets OutputMagnetic Disks

Random data access information retrieval without regard to the order in which it was recorded.


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• Diskettes– Also known as floppy disks– Read with a disk drive– Provide inexpensive, portable storage– Slow speed.– limited capacity (3 ½ floppy disk holds 1.44

MB)

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• Hard disks– Primary storage device in a computer– Non-removable, rigid disks that spin continuously

and rapidly – 2 or more aluminum platters– Each platter has 2 sides– Provide much faster access than a floppy disk– Data found in 9.5 ms or less– Drive capacity greater than 40 GB

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Illustrated Hard Disk

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• Removable high capacity disks– Speed of hard disk– Portability of floppy disk– Several variants have emerged– Ex. Zip disks

• High capacity floppy disk• Stores up to 750 MB of data

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Optical DisksUse laser beams to read and write bits of information on the disk surface

Not as fast as magnetic hard disksMassive storage capacity Very reliable


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CD-ROM Optical drives that read CD-ROMs

CD-R WORM media (write-once, read many)

CD-RW Can read CD-ROMs and write, erase and rewrite data onto CD-R & CD-RW disks


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DVD (Digital Versatile Disks)Store & distribute all kinds of dataHold between 3.8 and 17 gigabytes of information

DVD-ROM drives Can play DVD movies, read DVD data disks, read standard CD-ROMs, and play audio CDsBecause they’re read-only, they can’t record data, music, or movies

DVD-RAM drives Can read, erase, and write data (but not DVD video) on multi-gigabyte DVD-R (but not CD-R or CD-RW) media


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Solid State Devices

• Data is stored physically

• No magnets or laser

• No moving parts

• Very fast

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Solid-State Storage DevicesFlash memory is an erasable memory chip

Sizes range from 16 MB to 1 GBCompact alternative to disk storageContains no moving partsDesigned for specific applications such as storing pictures in digital camerasLikely to replace disk and tape storage


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• USB flash drives Can store up to hundreds of megabytes of

data. they plug into a computer’s USB port.

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Computer Systems: The Sum of Its Parts

Personal Computers: basic design classesTower systems

Tall, narrow boxes that generally have more expansion slots and bays than other designs

Flat desktop systems Designed to sit under the monitor like a platform

All-in-one systems (like the iMac) Combine monitor and system unit into a single housing


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iMac

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Portable computers Include all the essential components, including keyboard and pointing device, in one compact box


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Extending The Processors Power

• Standard computer ports– Keyboard and mouse ports– USB ports– Parallel– Network– Modem– Audio– Serial– Video

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Ports and Slots RevisitedThe system or motherboard includes several standard ports:

Serial Port for attaching devices that send/receive messages one bit at a time (modems)Parallel Port for attaching devices that send/receive bits in groups (printers)Keyboard/Mouse Port for attaching a keyboard and a mouse


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• Serial and parallel ports– Connect to printers or modems– Parallel ports move bits simultaneously

• Made of 8 – 32 wires• Internal busses are parallel

– Serial ports move one bit• Lower data flow than parallel• Requires control wires

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Serial Communications

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Parallel Communications

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Other ports are typically included on expansion boards rather than the system board:

Video Port used to plug in a color monitor into

the video boardMicrophone, speaker, headphone, MIDI ports used to attach sound equipmentLAN port used faster connection to a local-area network (LAN)


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• SCSI– Small Computer System Interface– Supports dozens of devices– External devices daisy chain

• allows several peripherals to be strung together and attached to a single port

– Fast hard drives and CD-ROMs

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Slide 78

Internal and external drives• Disks drives generally reside in bays

inside the system unit.

• Some PC have extra bays for additional internal hard drives or removable media

• External drives can be connected to the system through ports.

• Some portable enable you to Hot swap devices : remove and replace them without powering down.

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Extending the Processors Power

• Expansion slots and boards– Allows users to configure the machine– Slots allow the addition of new devices– Devices are stored on cards– Computer must be off before inserting

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Expansion Made Easy

With the PC open architecture -the design that enables you to add expansion cards and peripherals-

and the introduction of new interfaces, you can hot swap devices.


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• USB– Universal Serial Bus– Most popular external bus– Supports up to 127 devices

• including keyboard, mice, digital cameras, scanners, and storage devices can be chained together from a single USB port.

– Hot swappable– transmits a hundred times faster than a PC

serial port

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Extending the Processors Power

• FireWire– IEEE 1394– can move data between devices at 400 or more

megabits per second– High speed makes it ideal for data-intensive work like

digital video Cameras and video equipment– Hot swappable– Port is very expensive

• FireWire 800

- Recently introduced on high-end Macintosh systems

- offers 800 Mbps transfer speeds

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Putting It All TogetherA typical computer system might have several different input, output, and storage peripherals -- the key is compatibilityNetworks blur the boundaries between computersNetworked computers may have access to all the peripherals on a systemThe computer is, in effect, just a tiny part of a global system of interconnected networks


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Inventing the Future: Tomorrow’s Peripherals Tomorrow’s Storage

Smaller disks that hold more a single-electron memory chip the size of a

thumbnail that can store all the sounds and images of a full-length feature film

Tomorrow’s Output Flat-panel screens are replacing desktop CRTs at

an ever-increasing rate

Retinal display that works without a screen


You can count how many seeds are in the apple,but not how many apples are in the seed.—Ken Kesey, author of One Flew over the Cuckoo’s Nest

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Inventing the Future: Tomorrow’s Peripherals Tomorrow’s Input: Sensors

More sophisticated devices will serve as eyes, ears, and other types of sense organs for computer networks


Slide 86


Lesson Summary

Peripherals allow computer to communicate with the outside world and store information for later use information

The most common input devices today are the keyboard and the mouse

A variety of other input devices can be connected to the computer


A computer terminal is not some clunky old television with a typewriter in front of it. It is an interface where the mind and body can connect with the universe and move bits of it about.—Douglas Adams, author of The Hitchhiker’s Guide to the Galaxy

Slide 87


Lesson Summary

Output devices perform the opposite function: They accept strings of bits from the computer and transform them into a form that is useful or meaningful outside the computer

Storage devices are capable of two-way communication with the computer: Because of their high-speed random access capability are the most common forms of storage on modern computers


Slide 88


Lesson Summary Network connections make it possible for computers to

communicate with one another directly


As a rule, men worry more about what they can’t see than about what they can.—Julius Caesar

Documents

Slide 1 Computer Confluence 7/e Chapter 3 Hardware Basics: Peripherals © 2006 Prentice-Hall, Inc