technology in action
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Technology In Action. Te chnology In Action. Chapter 2 Looking at Computers: Understanding the Parts. Chapter Topics. Hardware components Input devices Output devices System unit Ergonomics. A Computer Is…. - PowerPoint PPT PresentationTRANSCRIPT
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Technology In Action
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Technology In Action
Chapter 2Looking at Computers: Understanding the Parts
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Chapter Topics
• Hardware components
• Input devices
• Output devices
• System unit
• Ergonomics
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A Computer Is…
• A device that accepts input, processes data, stores data, and produces output
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A Computer Is…
• A collection of hardware and software assembled for a certain purpose– The physical parts of a computer are
collectively known as hardware.– The programs or instructions used to tell the
computer hardware what to do are software.
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A Computer Is…
• Computers can store both data and instructions in memory.– Von Neumann architecture– A program is a set of hardware instructions
which are loaded into memory– Storing multiple programs in memory allows
you to switch between tasks– This ability distinguishes a computer from
other simpler devices
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Hardware
•System Unit
•Peripheral Devices
System UnitSystem Unit
Peripheral DevicesPeripheral Devices
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Input Devices
• Devices used to enter information or instructions into the computer– Keyboard– Mouse / pointing device– Microphone – Scanner– Digital camera
• Devices that are touched need to be cleaned regularly
Scanner
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Keyboard
• The QWERTY keyboard is standard on most PCs
• Enhanced features include number pad, function and navigation keys.
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Dvorak Keyboard
• Puts the most commonly used keys at “home keys”• Reduces distance of finger stretches
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Specialty Keyboards
• Laptops
• PDAs
• Wireless
• Ergonomic
Laptop
Ergonomic
PDA
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Mouse
• Rollerball mouse – Less expensive– Harder to keep clean
• Optical mouse– Needs no mouse pad– Doesn’t need as much cleaning– More expensive
• Trackball– Less movement of the wrist– Stationary on desk
• Wireless mouse– can be either roller or optical– security issues
Wireless
Optical
Trackball
Standard
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Inputting Sound• Microphone Input
– Teleconferencing– Voice over Internet– Voice Recognition
Microsoft Voice Recognition
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Input for the Physically Challenged
• Visually Impaired– Voice recognition– Keyboards with large keys– On-screen keyboards
• Motor control – Special trackballs– Head-mounted devices
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Other Input Devices• Scanners
– Text (OCR)– Images – Bar codes– RFID tags
• Digital cameras– Images – Video
Flatbed
Handheld
Camera Camcorder
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Output Devices
• Retrieving information from the computer's memory for human use
• Output devices – Softcopy (video,
sounds, control signals)
– Hardcopy (print)
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Monitor Types
• CRT Cathode Ray Tube
– Less expensive– Use much more space– Uses more energy– Better viewing angles
• LCD Liquid Crystal Display
– More expensive– Uses far less space– More energy efficient– Less viewable from an angle
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CRT Monitors• Uses picture tube (TV) technology
• Screen size – Diagonal measurement of the screen (15, 17, 19, 21 inches)
• Resolution – Sharpness of the image = the number of pixels that the screen can display (800 x 600, 1024 x 768, 1600 x 1200)
• Refresh rate – Speed at which the screen is refreshed (75Hz, 85Hz) Faster rate equals less flicker.
• Dot pitch - distance between pixels measured in mm (0.28, 0.32 mm) smaller is better
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Liquid Crystal Display
• Liquid crystal sandwiched between two transparent layers form images
• Used for notebook computers, PDAs, cellular phones, and personal computers
Polarizer
Color filter Color filter glass
Glass polarizer
Backlight
Liquid Crystal
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CRTs vs. LCDs
• CRTs have wider viewing angles
• better color accuracy• cheaper than LCDs• slightly faster display• Radiation a danger?
• LCDs are smaller and lighter
• take less power and give off less radiation
• have a larger viewable area
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Other Video Output
• Touch-screen monitors double as both input and output devices.
• Data projectors project a computer image to a large screen for sharing with large groups.
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Dot-matrix
Printers
Inkjet
Multifunction
Laser
Plotter
Thermal printer
• Impact printers– Dot-matrix
• Nonimpact printers– Inkjet– Laser – Multifunction
• Specialty printers– Plotters– Thermal printers
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Nonimpact Printers
• Inkjet– Less expensive device– Full color printing– Slower in pages per
minute (PPM)– More expensive per
page in B&W
• Laser– More expensive device– Black and White (Color
lasers are very expensive - CYMK)
– Faster in PPM– Less expensive in B&W
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Comparing Printers
• Speed - ppm
• Resolution - dpi
• Color / BW
• Memory - MB
• Cost of device
• Cost per page - ink or toner
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Outputting Sound
• Voice synthesis– Stephen Hawking
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Outputting Sound
• Speakers and Headphones
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The System Unit
Box that contains the central electronic components of the computer:– CPU/RAM/
motherboard– Expansion cards– Power supply– Storage devices
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The Front Panel• Drive bays• Memory card
reader• Floppy drive• Productivity
ports• Power button
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The Back
• Ports for peripheral devices
• Types of ports:– Serial– Parallel– VGA– USB– Connectivity
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Inside the System Unit
• Essential electronic components used to process data
• Types of components:– Power supply– Secondary storage– Motherboard– CPU– Expansion cards
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The Motherboard
• CPU (chips)
• RAM
• Expansion cards
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Expansion Cards
• Adds functions
• Provides new connections for peripheral devices
• Common types:– Sound– Modem– Video (VGA)– Network (NIC)
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Secondary StorageHard Disk Drive• Stores data and program
instructions• Permanent (nonvolatile)
storage• Storage capacities up to 250
GB and higher• Transfers data in
milliseconds (slower than RAM!)
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Setting it all up: Ergonomics
• Ergonomics refers to designing devices so they are comfortable and efficient to use
• Steps to follow:– Position monitor correctly– Use adjustable chair– Assume proper position
while typing (RSI)– Take breaks– Ensure adequate lighting
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The Digital Divide
• The Digital Divide is a social/political issue referring to the gap between people who have access to computers and the Internet and those who do not.
• Issues effecting this divide include age, economics, geographic location, etc…
• Attempted solutions - making computers available at public libraries, "One Laptop Per Child"
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GIGO
• GIGO stands for “Garbage In, Garbage Out”
• If invalid data is entered in a computer program, the resulting output will also be invalid.
• If a computer asked you to enter a letter and you enter a number, the results you would get back would probably be messed up, or "garbage."