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 printer Explain 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 – n umeric data & math symbols –Off – cursor movement Cursor Movement Keys

Keyboard Special 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

MICR Magnetic-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 original Exact 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 Recognition Bar Code Reader Photoelectric device Reads bar codes Inexpensive Reliable Where Used? –Supermarket – UPC –Federal Express

Optical Recognition Handwritten 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 display Liquid 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 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: 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 Printer Laser Printer

Transfers images to paper using a light beam Prints one page at a time dpi – High quality Speed –Personal laser printers: 8-10 ppm –Network laser printers: ppm –High-volume laser printers: up to 1000 ppm Black and white / color

Nonimpact Printer Ink-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 output Multiple sight and sound effects Speakers Sound card

Voice Output Speech 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 Output Speech 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/CAM Computer-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?