Input and Output: The User Connection Chapter 5 Objectives Describe the user relationship with computer input and output Explain how data is input to.

Input and Output:The User Connection

Chapter 5

Objectives

• Describe the user relationship with computer input and output

• Explain how data is input to a computer system and differentiate among various input equipment

• Describe how a monitor works and the characteristics that determine quality

• List and describe the different methods of computer output

• Differentiate among different kinds of printerExplain the function of a computer terminal and describe the types of terminals

Contents

• Input and Output

• Input

• Output

• Terminals

• Computer Graphics

• Ethics and Data

Input and Output

Input

• Users submit input data

Output

• Users get processed information

Input

• Data from the user to the computer

• Converts raw data into electronic form

Diversity of Input Methods

• Zebra-striped bar codes on supermarket items

• Word commands operate a forklift truck

• An order is entered using a pen on a special pad

• Time clock generates paycheck

• Data on checks are read and used to prepare a monthly bank statement

• Charge-card transactions generate customer bills

Keyboard

• Traditional– Looks like typewriter

with extra keys

• Non-traditional– Fast food restaurants– Each key represents a

food item rather than a character

Keyboard

Function Keys

• Give commands

• Software specific

Main Keyboard

• Typewriter keys

• Special command keys

Keyboard

• Numeric Keys– Num Lock – toggle – On – numeric data & math symbols– Off – cursor movement

• Cursor Movement Keys

KeyboardSpecial Keys

Enter

Esc

Alt

Ctrl

Caps Lock

Shortcut

Windows

Shift

Pointing Devices

• Position a pointer / cursor on the screen

• Controls drawing instruments in graphics applications

• Communicate commands to a program

Pointing Devices Mouse

• Types– Mechanical– Optical– Wireless

• Features– Palm-sized– 1 or 2 buttons– Wheel

Other Pointing Devices

• Trackball– Upside-down mouse– Ball on top– Roll ball with hand– Laptop computers

• Touchpad– Pressure-sensitive pad– Cursor moves as you

slide your finger– Laptop computers

Other Pointing Devices

Pointing stick• Pressure-sensitive post• Mounted between G and H keys on keyboard• Apply pressure in a direction to move cursor

Joystick• Short lever• Handgrip• Distance and speed of movement control pointer

position

Graphics Tablet

• Digitizing tablet

• Rectangular board

• Invisible grid of electronic dots

• Write with stylus or puck

• Sends locations of electronic dots as stylus moves over them

• Creates precise drawings

• Architects and engineers

Touch Screens

• Human points to a selection on the screen

• Types– Edges emit horizontal and vertical beams

of light that crisscross the screen– Senses finger pressure– Light pen for pointing

Touch Screens

• Kiosks– Self-help stations– Easy to use

– Where found• Malls• Disney World• Government offices

Pen-based Computing

• Small hand-held devices

• Electronic pen (stylus)– Pointer– Handwritten input

• Personal Digital Assistants (PDA)

Source Data Automation

• Special equipment to collect data at the source

• Sent directly to a computer

• Avoids need to key data

• Related input areas– Magnetic-Ink Character Recognition– Scanners– Optical recognition devices– Voice

MICRMagnetic-Ink Character Recognition

• Read characters made of magnetic particles

• Numbers on the bottom of checks

• MICR inscriber – adds characters to check that show amount cashed

Optical Scanners

• Optical recognition

• Light beam scans input data

• Most common type of source input

• Document imaging – converts paper documents to electronic form

• Converts snapshots into images

• Converts scanned picture into characters – OCR

Exact computer-produced replica of originalExact computer-produced replica of original

Types of Scanners

• Flatbed– One sheet at a time– Scans bound documents

• Sheetfeed– Motorized rollers– Sheet moves across

scanning head– Small, convenient size– Less versatile than flatbed– Prone to errors

Types of Scanners

• Handheld– Least expensive– Least accurate– Portable– User must move the scanner in a straight

line at a fixed rate– Wide document causes problems

Optical Recognition

• Optical mark recognition (OMR)– Mark sensing– Exams– Recognizes the location of the

marks

• Optical character recognition (OCR)– Light source reads special

characters– OCR-A is ANSI standard typeface

for optical characters

Optical Recognition Wand Reader

Retail stores

Libraries

Hospitals

Factories

Optical RecognitionBar Code Reader

• Photoelectric device

• Reads bar codes

• Inexpensive

• Reliable

• Where Used?– Supermarket – UPC– Federal Express

Optical RecognitionHandwritten Characters

Must follow rigid rules

• Size

• Completeness

• Legibility

Voice Input

• Speech Recognition

• Speech recognition devices– Input via a microphone– Voice converted to binary code

• Problems– Speaker-dependent– Voice training

Voice Input

• Changing radio frequencies in airplane cockpits

• Placing a call on a car phone

• Requesting stock-market quotations over the phone

• Command from physically disabled users

Voice Input

• Discrete work systems– Understand isolated words– Pause between words– Difficult for dictation

• Continuous work systems– Normal speaking pattern– Easy to use– Faster and easier to dictate than to key

Digital Cameras

• Photos stored in electronic form

• No film

• Point and shoot

• Edit

Output

• Information for the user

• Types– Screen – soft copy– Printer – hard copy– Voice– Sound– Graphics

Monitor

• Data that is entered appears on the screen

• Screen is part of the monitor

Monitor

Cathode Ray Tube (CRT)

Flat panel displayLiquid Crystal Display (LCD)

CRT

Raster scanning• Sweeping electron beams across the back of

the screen

• Phosphorous coating on back

• Glows when hit by a beam of electrons

• Phosphorous loses glow and image fades and flickers

• Image must be continually refreshed

CRT

Refresh rate / scan rate

• Number of times electron beams refreshes the screen

• 80-100 times per second adequate for clear screen image

• Process also used for television

CRT

Interlaced vs. Non-interlaced• Interlaced

– Refresh every other line on each pass– Lower refresh rate without flicker– Good for fixed graphics– Causes flutter with animated graphics– Inexpensive

• Non-interlaced– Refresh every line on each pass– Typical screen sold today

CRT

Color vs. Monochrome

• Color– Typical monitor sold today

• Monochrome– Green or amber on a contrasting

background– Less expensive than color

CRT

Resolution• Clarity of image

• Pixel (Picture element)– Dot on screen– Is addressable– Can be illuminated– More pixels means higher resolution

• Dot pitch– Distance between dots– Smaller distance means better quality image

CRT

Graphics Card/Graphics Adapter Board

• Plugs into expansion slot on motherboard

• Graphics card and monitor must be compatible for high quality image

CRT

Size• Measured diagonally

• Typical sizes– Office user: 15-17 inch– High-powered graphics user: 19 inch– High-end monitors: 21 inches and up

• Larger size– More expensive– More space on desktop– Reduces eye strain

Graphics Standards

• PCs

• Monitor

• Graphics boards

• Software

Help insure that the products work together

Graphics Standards

• SVGA (Super VGA)– Resolution – 800 x 600, 1024 x 768, 1280 x 1024,

1600 x 1200 pixels– 16 million colors– Number of colors displayed simultaneously limited

by amount of video memory

• XGA (Extended Graphics Array)– High resolution– Supports more simultaneous colors– Allows non-interlaced monitors

Flat-panel Screens

• Liquid Crystal Display (LCD)

• Primarily on laptops

• Moving to desktop

• Skinny (depth) regardless of size

Flat-panel Screens

• Crisp, brilliant images

• Easy on eyes

• No flicker

• Full dimension is useable

• More expensive that CRT monitors

Flat-panel Screens

• Active Matrix– Thin-film transistor technology (TFT)– Transistors for each pixel– Brighter image– Viewable from an angle

• Passive Matrix– Fewer transistors– Cheaper– Less power

Printer

• Produces information on paper

• Orientation– Portrait– Landscape

• Methods of printing– Impact– Nonimpact

Impact Printers

Line printer

One line at a time

High volume

Low quality

Dot-matrix printer

One character at a time

Nonimpact PrinterLaser Printer

Nonimpact PrinterLaser Printer

• Transfers images to paper using a light beam

• Prints one page at a time

• 600-1200 dpi – High quality

• Speed– Personal laser printers: 8-10 ppm– Network laser printers: 35-50 ppm– High-volume laser printers: up to 1000 ppm

• Black and white / color

Nonimpact PrinterInk-jet Printer

• Spray ink at paper

• Black and white / color

• Excellent graphics

• Good quality

• Slower than laser

Nonimpact Printer

Choose based upon:

• Speed

• Quality

• Black and white vs. color

• Price

Sound

Creates multimedia outputMultiple sight and sound effects

SpeakersSound card

Voice OutputSpeech Synthesis

• Enables machines to talk to people

• Types– Voice synthesizers– Voice output devices– Audio-response units

• Convert data in storage to vocalized sounds

• Synthesis by analysis – human sounds are stored and reproduced as needed

• Synthesis by rule – creates artificial speech

Voice OutputSpeech synthesis

Uses

• Automobiles

• Telephone surveys

• Catalog order is ready

• Your payment is late reminder

Music and Other Sounds

• MIDI (Musical Instrument Digital Interface)– Communicates between MIDI devices and

computer– Rules that produce and process digital music

signals– MIDI information tells synthesizer

• When to start and stop playing a note• Volume• Modulation

• Software is available for composing and editing per MIDI standard

Terminals

• Device that provides input and output capabilities

• Dumb terminal– Keyboard and monitor– Connects to host for processing

• Intelligent terminal– Keyboard, monitor, memory, and processor– Connects with host

• Point-of-sale terminal (POS)– Input and output device– Captures retail data

Computer Graphics

• Business

• Education

• Science

• Sports

• Computer art

• Entertainment

Business Graphics

• Types– Maps– Charts

• Help– Compare data– Spot trends– Make decisions quickly

• Attention-getting

• Updated instantaneously

• Rendered quickly

Video Graphics

• Animated graphics

• Prepared one frame at a time

• Examples– Cartoons– Commercials without

humans– Television network’s logo– Arcade games

CAD/CAMComputer-Aided Design

Computer-Aided Manufacturing

• CAD– Software creates 2-D and 3-D designs

• CAM– Controls production equipment

• CIM (Computer Integrated Manufacturing)– Bridge between design and manufacturing – CAD/CAM integrated into manufacturing process– Provides balanced, efficient production process

Ethics and Data

• Computer data can be– Used– Sold– Altered

• What is legal?