C OMPUTING

COMPUTING

COMPUTING

ESSENTIALS

ESSENTIALS

199920001999200019992000

Presentations by:Fred Bounds

Timothy J. O’Leary Linda I. O’Leary

44Input and OutputInput and Output

CHAPTER

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Competencies

After reading this chapter, you should be able to:

1. Explain the difference between keyboards and direct-entry input devices.

2. Describe the features of keyboards and the four types of terminals.

3. Describe direct-entry devices used with microcomputers.

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Competencies

4. Discuss voice recognition systems.

5. Describe monitors and monitor standards.

6. Describe printers (ink-jet, laser, thermal) and plotters (pen, ink-jet, electrostatic and direct-image)

7. Describe voice-output devices.

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Overview

• Two most important places for computer- human interface

• Computers can only work with binary language

• Input devices translate what we understand to a form acceptable to the computer

• Output devices do the reverse

Input: Keyboard versus Direct Entry

Input devices convert people-readable data into machine-readable form. Input may be by keyboard or direct entry.

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Data Entry

• Keyboard entry– Keys like typewriter to enter text and numbers– Data normally comes from an original or

source document

• Direct entry– Data in machine readable form at entry point

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Data Entry

• Entry methods– Point-of-sale (POS) methods - keyboard and

bar scanning – Wand reader– Platform scanner

A Point-of-sale A Point-of-sale transactiontransactionA Point-of-sale A Point-of-sale transactiontransaction

Keyboard Entry

In keyboard entry, people type input. There are four types of terminals: dumb, intelligent, network computer and Internet terminal.

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TraditionTraditional al

keyboardkeyboard

TraditionTraditional al

keyboardkeyboard

Escape keyEscape keyEscape keyEscape key

Navigation Navigation keyskeys

Navigation Navigation keyskeys

Function keysFunction keysFunction keysFunction keys

SpacebarSpacebarSpacebarSpacebar

Numeric keypadNumeric keypadNumeric keypadNumeric keypad

Windows keyWindows keyWindows keyWindows key

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Keyboard Entry

• Keyboards - besides alphanumeric, special purpose keys that toggle or work with the Control, Alt and Shift keys

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Keyboard Entry

• Terminals - input and output device connecting users to mainframe computers– Dumb terminal - no processor or local

storage– Intelligent terminal - CPU, memory and

storage; Net PC, or network computer

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Keyboard Entry

• Terminals - input and output device connecting users to mainframe computers– Network terminal - low cost alternative to

intelligent terminal– Internet terminal - or Web terminal,

accesses and displays Web pages on a television set

Direct Entry

Direct entry creates machine-readable data that can go directly to the CPU. Direct entry includes pointing, scanning and voice-input devices.

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Direct Entry

• Data is already in machine-readable format

• No keyboard or transcription device required

• Three categories– Pointing devices– Scanning devices– Voice-input devices

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Pointing Devices

• Mouse, trackball or touch-surface - cursor moves in response to rolling ball or moving finger Left buttonLeft buttonLeft buttonLeft button Right Right

buttonbutton

Right Right buttonbutton

Roller ballRoller ballRoller ballRoller ball

Retaining ringRetaining ringRetaining ringRetaining ring

CableCableCableCable

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Pointing Devices

• Mouse, trackball or touch-surface - cursor moves in response to rolling ball or moving finger

• Touch screen - screen recognizes position of touching finger

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Pointing Devices

• Mouse, trackball or touch-surface - cursor moves in response to rolling ball or moving finger

• Touch screen - screen recognizes position of touching finger

• Light pen - screen recognizes position of light-sensitive pen-like device

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Pointing Devices

• Digitizer - special pad and stylus used to capture images hand drawn

• Digital camera - image recorded digitally and stored on chips or disks; not yet film quality, but increasingly popular as prices drop

• Digital notebook - notepad that can capture handwriting and store it

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Digitizer: an Digitizer: an industrial designindustrial design Digitizer: an Digitizer: an industrial designindustrial design

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Pen-based computer: Pen-based computer: recording inventory recording inventory Pen-based computer: Pen-based computer: recording inventory recording inventory

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Scanning Devices

• Image scanner - images scanned and broken into digital code

• Fax machine - scanner codes images and sends them over the phone line

• Bar-code readers - photoelectric scanner reads vertical bars

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Image Scanner

• Identifies images on a page and converts them to digital electronic signals

• Increased usage in desktop publishing and for home use as well

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Fax Machines

• Fax machine - scans images and transmits them over phone lines to a receiving fax on the other end

• Fax modem cards in computers achieve same results without scanning capability

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Bar-Code Readers

• Photoelectric scanners that read vertical zebra-striped marks called bar codes

• The bar code is a unique identifier that links to a product code in the store’s computer

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Bar-Code Readers

• The computer contains the product description and price

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Scanning Devices

• Character and mark recognition devices– Magnetic-ink character recognition (MICR) - used

by banks to read magnetically encoded characters

– Optical-character recognition (OCR) - specially preprinted characters are read by OCR devices such as wand scanners

– Optical-mark recognition (OMR) - devices sense the presence or absence of marks, common for test scoring

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Voice-Input Devices

• Convert speech into digital code• Most common device is the microphone• Voice recognition systems

– Microphone, bundled with sound card and software

– Some voice recognition systems must be trained for user’s voice

– Some can translate from one language to another

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Voice Recognition Systems

• Continuous speech - used to issue commands to special application programs

• Discrete-word - permits users to dictate directly into a microcomputer

Output: Monitors, Printers, Plotters, Voice

Output devices convert machine-readable information into people-readable form.

Monitors

Monitor standards indicate screen quality. Some monitors are used on the desktop, others are portable.

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Monitor Standards

• VGA (“Video Graphics Array”) - 16 colors at 640 by 480

• Super VGA or SVGA (“Super Video Graphics Array”) - minimum resolution of 800 by 600, up to 1600 by 1200

• XGA (“Extended Graphic Array”) - resolution up 1024 by 768, over 18 million colors

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Cables

Cable Port Devices

Parallel printer, CD-ROMdrive, Zip drive

USB modem, joy stick,scanner

Cable Port Devices

Parallel printer, CD-ROMdrive, Zip drive

USB modem, joy stick,scanner

Serial mouse, modem, keyboard

Video monitor

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Color and Resolution Capabilities

Standard Pixels Colors

SVGA 800 x 6001024 x 768

256256

Standard Pixels Colors

SVGA 800 x 6001024 x 768

256256

VGA 640 X 480 16

XGA 1024 X 768 65,536

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Monitors

• Cathode-Ray Tubes - similar to television technology

• Flat-Panel Monitors - or liquid display (LCD) monitors– Passive-matrix or dual-scan - images

created by scanning the entire screen– Active-matrix - each pixel is individually

activated

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A desktop monitor: A desktop monitor: SVGA display SVGA displayA desktop monitor: A desktop monitor: SVGA display SVGA display

Printers

There are three types of printers: ink-jet, laser and thermal.

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Printers

• Ink-jet Printer– Sprays droplets of ink on paper to produce

text and images– Inexpensive

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Printers

• Laser Printer – Technology

similar to photocopier

– Laser beam creates images which are applied via toner to paper

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Printers

• Thermal Printer– Heat used to produce text and images on

heat-sensitive paper– Very high quality color option

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Printers

• Other Printers– Dot-matrix uses pins to produce dots on

paper to represent text and images– Chain printer - high speed printer for

minicomputers and mainframes

Plotters

Plotters are special-purpose drawing devices.

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Plotters

• Pen Plotter– Moving pen or pencil over

drafting paper– Least expensive– Slower speed and limited

capability

• Ink-Jet Plotter– Uses sprayed droplets of

ink– Faster

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Plotters

• Ink-Jet Plotter– Uses sprayed

droplets of ink– Faster– High quality– Quiet operation

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Plotters

• Electrostatic Plotter– Electrostatic charges

(rather than pens) produce dots on specially treated paper

– Paper is then developed

– Very fast– Hazardous chemicals

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Plotters

• Direct Imaging Plotter– Electrically heated

pins create images on heat-sensitive paper

– Expensive paper required

– Two-color output only

Voice-Output Devices

Voice-output devices vocalize prerecorded sounds.

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Voice-Output Devices

• Make sounds that resemble human speech but actually are using prerecorded vocalized sounds

• Components are often a sound card and a speaker system

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