Chapter 4: Input and Output. 2 Learning Objectives Explain the purpose of a computer keyboard and...

Chapter 4:

Input and Output

2

Learning Objectives Explain the purpose of a computer keyboard and the types

of keyboards widely used today. List several different pointing devices and describe their

functions. Describe the purposes of scanners and readers and list

some types of scanners and readers in use today. Understand how digital cameras differ from conventional

cameras. Explain how audio input is accomplished. Describe the characteristics of a display device and explain

some of the technologies used to display images. List several types of printers and explain their function. Understand which hardware devices are used for audio

output.

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Overview This chapter covers:

Different types of keyboards and pointing devices

Types of scanners, readers, and digital cameras and what they are used for

Audio input devices Types of display devices and how they work Types of printers and how they work Audio output

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Keyboards Keyboard: An input device containing keys, arranged in a

typewriter configuration, used to input letters, numbers, and other symbols Can be wired or wireless

Most PCs today are designed to be used with a keyboard Contains

Standard alphanumeric keys Numeric keypad Function keys Directional keys and special keys

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Keyboards

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Keyboards Keyboards are increasingly including alternate input tools

Touch pads Scroll wheels Some also include built-in display screens

Portable PCs and mobile devices often use: Thumbpad Slide-out keyboard Pen or touch input Portable keyboard Virtual keyboard is an emerging possibility

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Keyboards

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Pointing Devices Pointing device: An input device that

moves an onscreen pointer (arrow or insertion point) to allow the user to select objects on the screen

Usually buttons on the device are used to select objects

Common types of pointing devices: Mouse Electronic pen Touch screen

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The Mouse Mouse: A pointing

device the user slides along a flat surface to move a pointer around the screen and clicks its buttons to make selections Older mechanical

mice use a ball Newer optical or

laser mice track movements with light

Can be wireless

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The Electronic Pen and Stylus Electronic pen: Device used to select objects, as

well as to draw or write electronically on the screen

Also called tablet pen, digital pen, stylus Commonly used with pen-based PCs

Used to issue commands and input data If handwriting recognition is used, written text

can be converted to editable typed text

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Handwriting Recognition

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The Electronic Pen and Stylus

Also used with: Digital writing systems Graphics tablets Signature capture devices

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Touch Screens Touch screen: Display device that is

touched with the finger to issue commands or otherwise generate input to the connected PC

Used with: Desktop and portable PCs Mobile phones and mobile devices Interactive whiteboards Consumer kiosks

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Touch Screens

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Other Pointing Devices

Joysticks, gamepads, and other gaming devices

Trackballs Control buttons

and wheels Touch pads

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Scanners, Readers, and Digital Cameras

Source documents: Documents containing data that already exists in physical form (order form, photograph, invoice, check, or price label)

Source data automation: Capturing data directly from a source document Saves time Increases accuracy

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Scanners Scanner (optical scanner): Input device

that reads printed text and graphics and transfers them to a computer in digital form Can scan photos, documents,

drawings, (flat objects) Data is typically input as a single

image If optical character recognition (OCR)

is used, text is input as editable, typed text

Types of scanners Flatbed Drum

― Handheld― 3D

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Scanners Optical resolution: Quality of scanned

images Measured in number of dots per inch (dpi) Can often be specified when image is scanned Can be changed when scanned image is edited Varies with scanner used

Pixel: Smallest colorable area in an electronic image

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Barcode Readers Barcode readers: Input devices that

read barcodes Barcode: Machine-readable code

that represents data as a set of bars Common types

Universal Product Code (UPC) ISBN Code 39 POSTNET code High-capacity color barcode

(HCCB)

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Radio FrequencyIdentification Readers

Radio frequency identification (RFID): Technology used to store and transmit data located in RFID tags

RFID tag: Contains tiny chips and radio antennas Attached to objects for identification purposes Read by RFID readers Tags only need to be within range of the reader, rather

than in the line of sight Applications

Tracking inventory and assets Electronic tolls Electronic payments (Near Field Communication) Security

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Radio FrequencyIdentification Readers

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Optical Mark Readers (OMRs) Optical Mark Readers (OMRs): Input data

from special forms to score or tally exams, questionnaires, ballots

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Optical Character Recognition Devices

Optical Character Recognition (OCR): Reads optical characters that are designed to be identifiable by humans as well as OCR devices Most machines today are designed to read

several standard OCR fonts Used to process turnaround documents like

monthly bills

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Magnetic Ink Character Recognition (MICR) Readers

Magnetic ink character recognition (MICR) readers: Read MICR characters Used primarily for banking MICR readers read the special magnetic

characters and sort/process checks

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Biometric Readers Biometric data: Based on unique physiological

characteristics or personal trait Fingerprint Hand or face geometry Iris of the eye Voice or signature

Biometric readers: Used to input biometric data Can be stand-alone or built into another piece of

hardware (keyboard, mouse) Also being built into computers and storage devices to

allow access only by authorized individuals Most often used for access control and to verify

transactions

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Biometric Readers

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Digital Cameras Digital cameras: Record images on digital storage medium

rather than film Can either be still cameras or video cameras Typically use flash memory for storage Images can be edited, posted to a Web page, burned to a

CD or DVD disc, etc. Digital still cameras

Available in a wide variety of sizes and capabilities Photos can be transferred to a PC or printer Camera quality is measured in megapixels

Digital video cameras Digital camcorders PC video cameras (PC cams, Web cam)

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Digital Cameras

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Audio Input Audio input: The process of entering audio

data into the computer Voice (narrations, podcasts, etc.) Music (from CDs, MIDI keyboards, etc.)

Voice input systems (speech recognition systems) Enable a computer to recognize the human

voice Consist of a microphone or headset and

appropriate software Can be used to dictate text or commands into

a PC

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Voice Input Systems

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Display Devices

Display device: Presents output visually Monitor: Display device for a desktop PC Display screen: Screen built into a variety of

devices Notebook and handheld PCs, Mobile phones and mobile devices E-books readers, digital photo frames, and other

consumer devices, and many other devices Digital signage systems E-paper

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Display Devices

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Display Device Characteristics

Color vs. monochrome displays CRT vs. flat-panel display Size Screen resolution Wired vs. wireless 2D vs. 3D Digital TV and HDTV

capabilities Touch screen capabilities Video card being used determines some of the

characteristics (bit depth, video RAM, connections, etc.)

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Screen Resolution

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Flat-Panel Display Technologies

Liquid crystal displays (LCDs): Use charged liquid crystals between sheets of glass or plastic Requires backlighting

LED (Light emitting diode): Used in displays as well as a variety of consumer products

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Flat-Panel Display Technologies

Organic light emitting diode (OLED) displays: Use emissive organic material to display brighter and sharper images Do not need

backlighting Used with

consumer devices (portabledigital mediaplayers, TVs,etc.)

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Flat-Panel Display Technologies Special types of OLEDs

Flexible OLEDs (FOLEDs) Transparent OLEDs (TOLEDs) Phosphorescent OLEDs (PHOLEDs)

Interferometric Modulator Displays (IMOD): Essentially a complex mirror that uses external light to display images Designed initially for mobile phones and portable

devices Images are bright and clear, even in sunlight

Plasma displays: Use layers of gas to display images Most often used on large displays

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Flat-Panel Display Technologies

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Data and Multimedia Projectors Data projector: Display device that projects all

computer output to a wall or projection screen Most data projectors today can project video,

in addition to computer output Can be wireless or integrated into devices FogScreen systems projects on a thin layer of

fog Holographic projectors are in development

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Printers Printers: Produce hard copy Printer Characteristics

Printing technology used Impact vs. nonimpact

Color vs. black and white Personal vs. network printers Print resolution Print speed Possible connections Multifunction capabilities

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Printers

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Laser Printers

Laser printer: Uses toner powder and technology similar to that of a photocopier to produce images on paper The standard for business documents Print one entire page at a time Generally faster and have better quality than

ink-jet printers Can be black and white or color Common print resolution for laser printers is

between 600 and 2,400 dpi Use toner cartridges

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Laser Printers

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Ink-Jet Printers Ink-jet printer: Sprays droplets of ink to produce images on

paper Usually print in color Often the choice for home use Print fairly slowly, one line at a time Quality not quite as good as a laser printer Use ink-jet cartridges

Newer printers with full width printheads are much faster Potential applications for the future

Dispensing liquid metal, aromas, computer chips and other circuitry, “printing” human tissue

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Ink-Jet Printers

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Special-Purpose Printers Photo printers Barcode, label,

and postage printers

Portable printers

Plotters and wide-format ink-jet printers

3-D printers

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Audio Output Audio output: Output in the form of voice

or music Speakers Voice output systems Headphones and headsets Earphones and earbuds

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Summary

Keyboards Pointing Devices Scanners, Readers, and Digital Cameras Audio Input Display Devices Printers Audio Output