Hardware Basics:Hardware Basics:
Peripherals
3
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Chapter Outline
• Input: From Person to Processor
• Output: From Pulses to People
• Storage Devices: Input meets Output
• Computer Systems: The Sum of Its Parts
“We swim in a sea of information.”
Gary Snyder
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The Omnipresent Keyboard
Keyboards are used to input and manipulate information with keys such as Letters and Numbers…
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The Omnipresent Keyboard
…and Cursor Keys that allow you to move around the screen
…Function Keys that send special commands…
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Reading Tools
• Optical-mark readers• Bar-code readers
• Magnetic-ink character readers
• Wand readers
• Pen scanners
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Scanners
Digitizing the Real World
Audio digitizing andSpeech recognition software
Video digitizing
Sensing devices
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Scanners
Scanners capture and digitize images from external paper sources
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Video Digitizers
Video digitizers contain circuitry to digitize frames from camcorders and other video sources.
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Digital Cameras
Digital cameras turn real-world scenes into digital images that can be stored and manipulated by the computer
The images, stored in memory, can be transferred to a computer for either editing or storage
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Audio Digitizers
• Audio digitizers contain circuitry to digitize sounds from microphones and other audio devices.
• Spoken words, music, and sound effects can be captured.
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Sound
Video Monitor
ControllingOther Machines
Output: From Pulses to People
Paper
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Screen Output
• Video Monitor
– Also called Video Display Terminal (VDT)
– Image exists in video memory—VRAM
– Monitor size is measured diagonally across the screen
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• Images are made up ofdots called pixels forpicture elements
Pixels
• The number of pixelsaffects the resolutionof the monitor
• The higher the resolution,the better the image quality
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Color Depth (Pixel Depth)
• The amount of information per pixel is known as the color depth
– Monochrome (1 bit of information per pixel)
– Gray-scale (8 bits of information per pixel)
– Color (8 or 16 bits of information per pixel)
– True color (24 or 32 bits of information per pixel)
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Examples of Color Depth
1-bit depth
16-bit depth8-bit depth
4-bit depth
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CRT (cathode ray tube)
LCD (liquid crystal display)
Classes of Monitors
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A CRT is a television-style monitorfeaturing:
CRT (Cathode Ray Tube)
– Clear image
– Quick response time
– Low cost
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• LCDs are flat-panel monitors
• Features include:– Lighter weight
– More compact
• More expensive
• Dominate the portable computer market
LCD (Liquid Crystal Display)
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Paper Output
• Paper output is sometimes called hard copy
• Hard copy can come from one of two kinds of printers:
– Impact printers
– Nonimpact printers
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• Line printers– Used by mainframes for
massive jobs
– Limited characters available
Impact Printers
• Dot-matrix printers– Image formed from dots printed on paper
– Good for text and graphics
– Inexpensive
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Nonimpact Printers
• Laser printers
– Image transferred to paper with laser beam
– Faster and more expensivethan dot-matrix
– High-resolution hard copy
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Other Nonimpact Printers
• Ink-jet
– Dots of ink are sprayed onto the paper to form the image
– High-resolution hard copy
– Some models print can print colorphotographs
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Rules of Thumb:Ergonomics and Health
• Choose equipment that’s ergonomically designed
• Create a healthy workspace
• Build flexibility into your work environment
• Rest your eyes
• Stretch tight muscles
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Output You Can Hear
• Synthesizers can beused to generate music and sounds
• Many computershave synthesizers
• Sound cards havebuilt-in synthesizers
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• Output devices turn bit patterns into non-digital movements
Controlling Other Machines
— Robot arms— Telephone switchboards— Transportation devices— Automated factory
equipment— Spacecraft
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Storage Devices:Input Meets Output
• Peripherals with both input and output functions provide semi-permanent storage for data
• Examples include:
– Magnetic tape and disks
– Zip, Jaz and SuperDisks
– Magneto-optical disks
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Optical Disks
• Optical disks use laser beams rather than magnets to read and write information
• CD-RW drives can write, erase, and rewrite CDs
• CD-ROM drives are optical drives that read CD-ROMs
• DVD’s can hold between 3.8 and 17 gigabytes of data, they are replacing CD-ROMs
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Alternatives
• Flash memory
– Compact alternative
– No moving parts
– May eventually replace disk and tape storage
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Ports and Slots…again
• The system board (motherboard) includes several ports:– Serial Port for attaching devices that
send/receive messages one bit at a time (modems)
– Parallel Port for attaching devices that send/receive bits in groups (printers)
– Keyboard/Mouse Port
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Ports and Slots…again
• Other ports that are generally included on expansion boards instead of the system board:
– Video Port used to plug in a color monitor into the video board
– Microphone, speaker, headphone, MIDI ports used to attach sound equipment
– SCSI port allows several peripherals to be strung together and attached to a single port
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Internal and External Drives
• Hard drive
• CD or DVD
• Floppy disk
• Zip Drive
• SCSI port
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Expansion Made Easy
• USB and Firewire ports allow multiple devices to be connected to the same port and to be hot swapped:
– USB (Universal Serial Bus) transmits a hundred times faster than a PC serial port
– Firewire (IEEE 1394) can move data between devices at 400 or more megabits per second
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Putting It All Together:Networks
• Networks blur the boundaries between computers
– Networks can include hundreds of different computers
– Can span the globe by using satellites and fiber optic cables
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