Chapter 3 Interfaces Between You and the Computer © The McGraw-Hill Companies, Inc., 2000 Input/Output Hardware

Ch 3© The McGraw-Hill Companies, Inc., CCI Overview I/O usage Input hardware Output hardware Combined input and output devices

Ch 3© The McGraw-Hill Companies, Inc., CCI Input Hardware Three types: keyboard, pointing, and source-entry

Ch 3© The McGraw-Hill Companies, Inc., CCI Keyboard Standard keys –type characters –CAPS lock Cursor-movement keys –arrows, page up, page down Numeric keys –for calculating (Num Lock) Function keys –“F” keys, for software functions Special-purpose keys –Alt, Ctrl, Shift, Escape, Enter 

Ch 3© The McGraw-Hill Companies, Inc., CCI Source-data Entry Devices Scanners, bar-code scanners, fax machines, imaging systems Voice-recognition devices Audio input devices Electronic cameras Sensors Human-biology input devices

Ch 3© The McGraw-Hill Companies, Inc., CCI More Keys and Indicators Delete key Insert key Status lights Secondary arrows in numeric pad 

Ch 3© The McGraw-Hill Companies, Inc., CCI Function Keys Issue commands Defined by the software program Also used by some computers during boot up to access the options for CMOS/BIOS settings 

Ch 3© The McGraw-Hill Companies, Inc., CCI Ergonomics Keyboards Mice Keyboard wrist pads Monitor placement Proper seat adjustment Proper monitor viewing adjustment

Ch 3© The McGraw-Hill Companies, Inc., CCI Mice Can be wireless controlled by infrared or radio signals Can have a programmable wheel Can have additional buttons

Ch 3© The McGraw-Hill Companies, Inc., CCI Mice Actions Point Click Double-click Drag Drop Right-click Programmable

Ch 3© The McGraw-Hill Companies, Inc., CCI Which point device is best? Mouse –Relatively inexpensive –Little finger movement –Foot print required is large Trackball –Uses less space –Less movement than mouse –Increased finger movement Touchpad –Less dust prone –More precision

Ch 3© The McGraw-Hill Companies, Inc., CCI Other Input Light Pen –light-sensitive stylus –use on display screens and... Digitizing Tablets –for graphic design, computer animation, and engineering diagramming Pen-based Systems –enter handwriting and marks into the computer

Ch 3© The McGraw-Hill Companies, Inc., CCI Types of Pen-Based Systems Gesture recognition or electronic checklists Handwriting stored as scribbling Handwriting converted to typed text –similar to voice-recognition, requires training the software Handwriting, converted without training, to typed text –not that accurate at this point

Ch 3© The McGraw-Hill Companies, Inc., CCI PDAs Pen-based systems are most commonly used it in PDAs. Or Personal Digital Assistants, such as 3COM Palm III

Ch 3© The McGraw-Hill Companies, Inc., CCI Source-Data Entry Does not require keystrokes Direct entry into computer often is more accurate Main devices –Bar-code readers –Mark and character recognition devices –FAX machines –Imaging systems

Ch 3© The McGraw-Hill Companies, Inc., CCI Bar-Code Vertical striped marks on most manufactured products Often seen is a Universal Product Code, as seen in North America and Australia

Ch 3© The McGraw-Hill Companies, Inc., CCI Scanning Devices Bar-core readers –Photoelectric scanners that translate code symbols into digital code MICR –Magnetic-ink character recognition numbers such as on checks

Ch 3© The McGraw-Hill Companies, Inc., CCI More input devices OMR –Optical mark recognition reads marks and converts them into usable form –can now include black pen as well as pencil, depending upon the reader OCR –Optical character recognition uses specific character sets, converting them into machine- readable form

Ch 3© The McGraw-Hill Companies, Inc., CCI Other input devices FAX machines –facsimile transmission machine scans an image, then sends those electronic images over telephone lines Imaging systems –Image or graphic scanners convert text, drawings, photographs into digital form which can then be transmitted elsewhere

Ch 3© The McGraw-Hill Companies, Inc., CCI Imaging Systems Used in Desktop Publishing Multimedia Development Include scanners –External: flatbed, drum, or handheld –Internal: slide and photo

Ch 3© The McGraw-Hill Companies, Inc., CCI Voice Recognition Using as microphone or telephone Converts to digital code Saves typing input Current technology up to 98%

Ch 3© The McGraw-Hill Companies, Inc., CCI Voice Recognition Keys after signal processing: –Phonetic models –Dictionary –Grammar –Search –Output

Ch 3© The McGraw-Hill Companies, Inc., CCI Audio Input Devices Records or plays analog sound Translates for digital storage and processing

Ch 3© The McGraw-Hill Companies, Inc., CCI Audio Boards Also called sound cards Some motherboards have built-in audio boards Three major standards –SoundBlaster –Ad Lib –Windows

Ch 3© The McGraw-Hill Companies, Inc., CCI MIDI Boards Most support MIDI –musical instrument digital interface MIDI boards –used for multimedia applications

Ch 3© The McGraw-Hill Companies, Inc., CCI Video and Photographic Support Most are analog –frame-grabber video card –full-motion video card Digital video growing rapidly Advent of USB ports –rapid increase in digital cameras All-in-one cards –provide sound and video

Ch 3© The McGraw-Hill Companies, Inc., CCI Video Input Digital video –can be limited to the speed of the computer and its ability to provide a consistent and high enough frames-per-second –minimum to provide full- motion is 24 frames per second

Ch 3© The McGraw-Hill Companies, Inc., CCI Digital Cameras Use charge-coupled device (CCD) –light-sensitive photo cells Smallest 1/8th size of a 35 mm frame Up to 35 mm frame size Approaching image quality of 35mm

Ch 3© The McGraw-Hill Companies, Inc., CCI Sensors Collect specific kinds of data directly from the environment Transmit data to a computer for processing and consolidation Under highways for traffic control Within buildings for temperature control

Ch 3© The McGraw-Hill Companies, Inc., CCI Human-Biology Input Devices Identification through fingerprint, voice intonation, retinal image Line-of-site systems Cyber gloves and body suits

Ch 3© The McGraw-Hill Companies, Inc., CCI Multimedia Input Needs Sound card Microphone Graphics scanner Video capture card

Ch 3© The McGraw-Hill Companies, Inc., CCI Input Controls Garbage in, garbage out Manual and computer-based controls Software often uses internal software tables to validate data input Reasonableness tests coded Care should be taken to ensure system is not too restrictive

Ch 3© The McGraw-Hill Companies, Inc., CCI Output Hardware What are the main characteristics of printers, plotters, multifunction devices, display screens, and audio output devices?

Ch 3© The McGraw-Hill Companies, Inc., CCI Printers Impact printers –draft –near-letter quality –line printers Non-impact printers –laser –ink-jet

Ch 3© The McGraw-Hill Companies, Inc., CCI Laser Printers Often can be improved with additional memory to handle increased office requirements Page description standards –PS Adobe Post Script –HPGL Hewlett-Packard Graphic Language

Ch 3© The McGraw-Hill Companies, Inc., CCI Ink-Jet Printers Slower, but less expensive than laser printers Bubble-jet variation –uses heat to force inks through print head Cartridges are often implemented in the following ways –single holder can often print color by switching cartridges

Ch 3© The McGraw-Hill Companies, Inc., CCI Printer Cartridge Variation –double holder can often print color and photo quality by replacing cartridges –quad holder uses black, plus three different color cartridges, or four color cartridges

Ch 3© The McGraw-Hill Companies, Inc., CCI Plotters Produce high-quality graphics, often on large formats Two basic types –ink-jet plotter slower, output on continuous drum –electrostatic plotter paper lies partially flat, similar to a photocopier process

Ch 3© The McGraw-Hill Companies, Inc., CCI Printer or Plotter Installation Some drivers come preset within a BIOS Some come on included diskette or CD Often, more up-to-date drivers can be found from the manufacturer’s Web site Newer drivers than default drivers, such as keyboards or mice, may provide additional functionality

Ch 3© The McGraw-Hill Companies, Inc., CCI Multifunctional Printer Technology: All for One Often printing, scanning, copying, and faxing May not perform each function as quickly or as well as individual devices Statistically the repair record of these devices is equal to that of individual devices

Ch 3© The McGraw-Hill Companies, Inc., CCI Monitors The softcopy output Display adapters/video monitors have their own video chips and RAM CRTs –cathode ray tubes –also in television sets

Ch 3© The McGraw-Hill Companies, Inc., CCI Flat-Panel Screens Thinner, less weight Technologies used include: –Liquid crystal display (LCD) –Electroluminescent display (EL) –Active-matrix or dual-scan (passive-matrix) using transistors

Ch 3© The McGraw-Hill Companies, Inc., CCI Screen Clarity Standard screen resolutions –640 x 480 –800 x 600 –1024 x 768 –1280 x 1024 –1600 x 1200

Ch 3© The McGraw-Hill Companies, Inc., CCI Changing screen resolutions and refresh rates Consult manual for resolution and refresh rates prior to changing, as monitors may be damaged at ranges beyond capabilities

Ch 3© The McGraw-Hill Companies, Inc., CCI Dot Pitch & Refresh Rate Closer the pixels, the crisper the image Less than.31 mm provides clear viewing Multimedia and desktop publishing monitors often.25 mm pitch Refresh rate should be at least 72 Hz to avoid eye fatigue

Ch 3© The McGraw-Hill Companies, Inc., CCI Color Monochrome –black on white, white on black –amber on black –green on black Color monitors or RGB (red, green, blue) –between 16and 16.7 million color –based upon color depth

Ch 3© The McGraw-Hill Companies, Inc., CCI Monitor standards VGA –video graphics display –at 640 x 480 supports 4-bit color SVGA –at 1024 x 768 supports 8-bit color XGA –at 1024 x 768 supports 24-bit or true color

Ch 3© The McGraw-Hill Companies, Inc., CCI Monitor capacity and trade-off The more colors and the higher the refresh rate the harder the video card or adapter has to work The higher the color settings the slower the adapter The adapter and monitor must be compatible, including whether analog or digital

Ch 3© The McGraw-Hill Companies, Inc., CCI Future Display Technology High Definition Televisions (HDTV) –1920 x 1080 Field Emission Display (FED)

Ch 3© The McGraw-Hill Companies, Inc., CCI Audio Output Hardware Voice Output –Speech coding –Speech synthesis sounds called phonemes Sound Output –Digitized sounds –Beeps to music

Ch 3© The McGraw-Hill Companies, Inc., CCI Multimedia Output Needs Sound or audio card Headphones Speakers

Ch 3© The McGraw-Hill Companies, Inc., CCI In & Out: Devices That Do Both Dumb terminals Intelligent terminals –processing capability but no storage Point-of-Sale (POS) Terminals Automated Teller Machines

Ch 3© The McGraw-Hill Companies, Inc., CCI Smart and Optical Cards Smart Cards –Credit-card like with microprocessor Touch screens Future –retinal displays more common