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Input
any data or instructions that are used by a computer
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Input devices
hardware used to translate words, sounds, images, and actions that people understand into a form that the system unit can process
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optical mouse
no moving parts
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trackball (roller ball)
control the pointer by rotating a ball with your thumb
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multitouch screens
- touch by more than one finger
- rotate graphical objects with your hand
- zoom in and out by pinching and stretching your fingers
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scanning devices
- convert scanned text and images into a form that the system unit can process
- optical scanners
- card readers
- bar code readers
- character and mark recognition devices
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optical scanners
- accepts documents consisting of text and/or images and convert them to machine-readable forms
- flat-bed scanner
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card reader
interprets encoded info stored on cards, credit cards, debit cards
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magnetic card reader
thin magnetic strips on the back of the card
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radio frequency card readers
RFID (radio frequency identification) microchip contains the user's encoded info
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magnetic-ink character recognition
(MICR)
banks used to automatically read the unusual numbers on the bottom of checks and deposti slips
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optical-mark recognition (OMR)
- sense pencil marks
- score standardized multiple choice tests
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audio input devices
- convert sounds into a form that can be processed by the system unit
- microphone
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voice recognition systems
- use microphone, sound card, and special software
- use voice commands
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Clarity
most important characteristic of a monitor
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resolution
the higher the resolution (the more dots, pixels) the clearer the image
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Dot (pixel) pitch
- the distance between each pixel
- lower the pitch the clearer the images
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active matrix
thin film transistor (TFT)
- each pixel is independently activated
- better clarity
- more expensive
- require more power
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cathode-ray tubes (CRT)
- similar in size and technology to televisions
- low cost and excellent resolutions
- bulky and less energy efficient
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printer resolution
dpi (dots per inch)
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printer speed
measure by number of pages per minute
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printer memory
used to store printing instructions and documents waiting to be printed
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ink jet printer
- spray ink at high speed onto the surface of paper
- most widely used
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laser printer
use laser light beam to produce image with excellent letter and graphics quality
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personal laser printer
- less expensive
- used by single users
- prints 15-17 pages/min
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shared laser printers
- used by a group of users
- 50 pages/min
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digital music players
devices ofr storing, transferring, and playing audio files
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Voice over (VOIP)
- also known as telephony
- transmission of telephone calls over computer networks
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