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IS 2101Fall 2010

Chapter 2

Looking at Computers:

Understanding the Parts

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Chapter Topics

• Functions of a computer• Data versus information• Bits and bytes• Input devices• Output devices• System unit• Ergonomics

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Computers Are Data Processing Devices

• Computer’s four major functions: Gathers data (users input data) Processes data into information Outputs data or information Stores data and information

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Data vs. Information

• Data: Representation of a fact or idea • Information: Organized, meaningful data

Bits and Bytes: The Language of Computers

• Bit Binary digit 0 or 1

• Byte 8 bits

• Each letter, number, and character = a string of eight 0s and 1s

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How Much Is a Byte?

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Computer Software

• Software: Programs that enable hardware to perform different tasks Application software System software

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Computer Hardware

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Input Devices• Devices used to enter information or instructions

into the computer Keyboard Mouse/

pointing device Stylus Scanner Digital camera Microphone

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Keyboards

• The QWERTY layout is standard on most PCs

• Enhanced keyboard features include number, function, and navigation keys.

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Dvorak Keyboards

• Puts the most commonly used keys on “home keys”• Reduces distance of finger stretches

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Specialty Keyboards

• Notebook keyboard• PDA stylus• Tablet PCs• Wireless keyboard

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Mice

• Optical mouse Needs no mouse pad Doesn’t need cleaning Is more expensive

• Trackball Easier on wrists Stays stationary on desk

• Wireless Use radio or light waves

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New Mouse Features

• Instant viewer• Magnifier• Customizable

buttons• Web search

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Other Input Devices

• Scanners Text Images

• Digital cameras Images Video

Flatbed scanner

Handheld scanner

Digital camera

Camcorder

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Other Input Devices

• EPOS Digital Pen• Web Cam

Live video

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Inputting Sound

• Microphones used for: Podcasts Video-conferencing Internet phone calls Speech recognition

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Input Devices for the Physically Challenged

• Visual impairments Voice recognition Keyboards with large keys On-screen keyboards

• Motor control issues Special trackballs Head-mounted devices

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Output Devices

• Send processed data out of the computer Monitors Printers

• Output devices make: Soft copies (video, sounds, control signals) Hard copies (print)

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Monitor Types

• CRT Cathode Ray Tube Less expensive Use much more space Use more energy Offer better viewing angles Legacy technology

• LCD Liquid Crystal Display More expensive Use far less space More energy efficient Less viewable from an angle

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Key Monitor Features

• Screens are grids made up of millions of pixels.

• LCDs: Liquid crystal is sandwiched between two transparent layers to form images

• CRTs: Pixels illuminated by electron beam that passes back and forth across screen

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LCD Quality Factors

• Resolution

• Passive vs. active matrix display

• Viewing angle

• Contrast ratio

• Brightness

• Response time

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LCD versus CRT

• LCD monitors: take up less space are generally brighter cause less eyestrain use less energy weigh less

• CRT monitors: used to offer more resolutions used to produce better color and clarity

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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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Printers

• Impact printers Dot-matrix

• Nonimpact printers Inkjet Laser

• Specialty printers Multifunction Plotters Thermal printers

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Nonimpact Printers

• Inkjet Less expensive

device Print high-quality

color images cost effectively

• Laser More expensive device Faster printing speed Less expensive per

page in B&W Color lasers are

becoming less expensive

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Choosing a Printer

• Speed (ppm)• Resolution (dpi)• Color output• Memory• Use and cost• Cost of consumables

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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

• Power control• Drive bays• Memory card

reader• Productivity

ports

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Power Controls

• Power-on button: Turns on system, should not be used to turn it off

• Other options: Sleep mode Hibernation Warm boot

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Drive Bays

• Internal drive bays: Cannot be access from outside the system Reserved for internal hard drives

• External drive bays: Can be accessed from outside the system CD or DVD drives Floppy and Zip drives

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Hard Disk Drive

• Permanent (nonvolatile) storage• Internal or external versions

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Flash Drives/Flash Memory

• Flash drives (jump drives) Newer storage

alternative Plug into USB ports

• Flash memory cards Slide into slots in the

system

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Storage Media Capabilities

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On the Back

• Ports for peripherals• Types of ports:

Serial and parallel Audio and video USB FireWire Connectivity

• Ethernet• Modem

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Inside the System Unit

• Essential electronic components used to process data

• Types of components: Power supply Hard disk drive Motherboard CPU Expansion cards

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The Motherboard

• CPU• RAM• Expansion

cards and slots• Built-in

components

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Central Processing Unit (CPU)

• Referred to as the “brains” of the computer• Controls all functions of the computer• Processes all commands and instructions• Can perform billions of tasks per second

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Memory Module

• Random access memory (RAM)• Stores instructions and data• Temporary (volatile) storage• Operates in nanoseconds

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Expansion Cards

• Add functions• Provide new connections for peripheral devices• Common types:

Sound Modem Video (VGA) Network (NIC)

Specialty Computers

• Mainframes• Supercomputers• Embedded computers

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Setting It All Up: Ergonomics

• Ergonomics: minimizing injury or discomfort while using the computer

• Steps to follow: Position monitor correctly Use adjustable chair Assume proper position while typing Take breaks Ensure adequate lighting

Ergonomics and Mobile Devices

Mobile devices present ergonomic challenges

Ergonomic “Disease” Cause

Blackberry thumb Thumb typing without breaks or stretching can cause DeQuervains’ tendinitis in the thumbs.

iPod deafness Listening through ear buds for prolonged periods at a volume of 80 decibels or more can cause deafness.

Cellular blindness Extended viewing on tiny screens can cause eye strain and/or dry eyes.

Laptop thighs Resting a laptop directly on your lap for extended periods of time can result in 1st and 2nd degree burns.

Laptop shoulder Large, heavy, one-strap laptop bags can result in neck, shoulder, and back pain and/or strain.

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Chapter 3 Summary Questions

• What exactly is a computer, and what are its four main functions?

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Chapter 3 Summary Questions

• What is the difference between data and information?

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Chapter 3 Summary Questions

• What are bits and bytes, and how are they measured?

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Chapter 3 Summary Questions

• What devices do you use to get data into the computer?

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Chapter 3 Summary Questions

• What devices do you use to get information out of the computer?

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Chapter 3 Summary Questions

• What’s on the front of your system unit?

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Chapter 3 Summary Questions

• What’s on the back of your system unit?

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Chapter 3 Summary Questions

• What’s inside your system unit?

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Chapter 3 Summary Questions

• How do you set up your computer to avoid strain and injury?