Input and Output The User Connection Chapter 5

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 Main Keyboard • Give commands • Typewriter keys • Software specific • Special command keys

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

Keyboard Special Keys Shift Caps Lock Ctrl Alt Esc Enter Windows Shortcut

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

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 • 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 Help insure that the products work together • PCs • Monitor • Graphics boards • Software

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 Dot-matrix printer One line at a time One character at a time High volume Low quality

Nonimpact Printer Laser Printer

Nonimpact Printer Laser 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 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?