Post on 31-Oct-2014
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IT Fundamentals 1
1. INPUT Much conversion of language occurs in a computer system
(English)
DATA INPUT DEVICE
(binary)
CPU
(binary)
OUTPUT DEVICE INFO
(English)
Input/ OutputInput/ Output
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Two types of input : Data and InstructionsTwo types of input : Data and Instructions
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Input DevicesInput Devices
Provides:-entry of data-Conversion into data format
Most obvious = human + KEYBOARD
Human data entry is called non-direct input.Machines make better input devices.
DIRECT ENTRY, or SOURCE DATA AUTOMATION.
Need to be: Accurate, reliable and easy to
use, fast
Human and keyboard is the most used input device
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Examples of Direct Entry Input DevicesExamples of Direct Entry Input Devices
- flat bed or hand-held- Similar to a photocopier- Reads page as a grid of dots- stores data as a "picture" MICR : Used with cheques
Scanners
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Examples of Direct Entry Input DevicesExamples of Direct Entry Input Devices
Barcode Readers:
Sit-in-the-Counter type - Reads standard or customised barcodes- Can also purchase software to print barcodes.
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Input TypesInput Types
a.
Data Collection Devices:Stocktake devicesAutomatic counters
Web CamsVideo camera whose output displays on a web page
Digital Camera
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Other Input DevicesOther Input Devices
a.
Sensors-Encode a physical event into data
Pointing DevicesMouse
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Other Input DevicesOther Input Devices
TouchPadPointing StickLight Pen
Trackball
• Similar to mouse
Joystick• games
Touch screens• screen 'divided' into areas• area selected by touch• easy to use• cannot have areas too small• screens get dirty (many uses)
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Voice InputVoice Input
Voice Input• hands free• trained for each voice
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OutputOutput
Four common type of output are text, graphics, audio and video.
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OutputOutput
Output Devices
Digital signals from computer are converted into human readable form.
Hard Copy - printer- plotter
Soft Copy- screen- voice
PrintersImpact printers•Impact a solid image of a character onto an inked ribbon up against the paper.
Non-impact printers• no physical contact between paper and printing device• dot matrix concept used to form characters
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OutputOutput
Ink jet• quiet
Thermal• special paper• expensive to run
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OutputOutput
Laser• high speed, high quality• page printers• need enough memory to hold an entire page• 600 to 2400 dpi
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OutputOutput
CRT Monitors
•Raster scan technology
•An electron beam moves back and forward across the back of the screen
•This causes dots on the front of the screen to glow, producing an image
•Available in various sizes 15 – 22 inches
•Flat and curved screens
Resolution
•Increase pixels/screen
•Increase resolution (better image)
•CRT monitors ( 1280 X 1024 pixels)
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OutputOutput
LCD Monitors•Contains liquid crystals between 2 sheets of material
•An electric current passes through the crystals causing them to twist, block light waves and create an image.
•Uses less than one third the power of a CRT monitor
•Lightweight and compact (mobile users)
Gas Plasma Monitors
•A layer of gas instead of liquid crystals
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Other Output DevicesOther Output Devices
Data Projectors
Fax Machine
•Transmits and receives documents over the telephone line
Multifunction devices
•Printer, scanner, copy machine and fax machine all in one
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SECONDARY STORAGESECONDARY STORAGE
Control Unit works on programs/data in RAMPOWER OFF ... RAM OFFBye Bye AssignmentHowever blocks of memory can be saved/read on secondary storage.
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Secondary Storage Media and Devices
Floppy DisksHard DisksTape and Tape driveCartridge tapeCD-ROMDVD ROMMagnetic-Optical drivePC CardsSmart Cards
SECONDARY STORAGESECONDARY STORAGE
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FLOPPY DISKS:FLOPPY DISKS:
• Circular piece of plastic• Made up of tracks & sectors• 512 bytes in each sector
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Maintaining data stored on a disk
• Made up of platters, cylinders and sectors• head 'floats' on surface• capacities range up to 200+ GB
HARD DISKSHARD DISKS
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OPTICAL STORAGE TECHNOLOGY• high capacity is ideal for storage of the very large sound, graphics and video files• when recording data, laser light burns pits on CD• when reading data, pits will not reflect light (binary bit 0) but lands will reflect light (binary bit 1)
CD-ROM (compact disk read-only memory)- 650 MB of information
DVD (digital video disk) - 4.7 GB – 17 GB
Hard Disk Vs Floppy Disk
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Optical Storage
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Optical Storage
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TAPE
• Thin ribbon of plastic• Sequential storage – mainly for backup
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OTHER TYPES OF STORAGE DEVICESOTHER TYPES OF STORAGE DEVICES PC cardsPC cards
• Small, credit card-sized cards that fit into PC Card expansion slots •Used for storage, communications and additional memory.• Most often used with portable computers• Can store more than 300 MB of data
Smart Cards• Credit card-sized devices that contain a microprocessor• Microprocessor can store up to 8,000 bytes of information.• Examples of uses - prepaid telephone card, employee time card
USB Drive•Flash memory storage device that plugs in a USB port
•Small and lightweight