1. PAAVAI COLLEGE OF EDUCATION
Paavai Nagar, Nh-7,pachal, Namakkal - 637018
POWER POINT PRESENTATION
2011-2012
2. PAAVAI COLLEGE OF EDUCATION
Paavai Nagar, Nh-7,pachal, Namakkal - 637018
POWER POINT PRESENTATION
NAME : S.MANIKANDAN
OPTIONAL : COMPUTER SCIENCE AND MATHS
ROLL NO : 038
5. Input Devices
• Let users enter data into an information system.
• Keyboard, keypad
• Mouse, touchpad
• Bar code reader
• Touch screen
• Data tablet
• Scanner, camera
• Voice recognition
6. Input Devices
• Keyboard, keypad
– QWERTY layout. Designed to be as inefficient as
possible to stop fast typists jamming the early
typewriters
– Dvorak – more efficient key layout puts most
commonly used keys on the home row. Rare!
7. Input Devices
• Mouse, trackball
– Designed for GUI OS
– Ball mouse superseded by optical
– RSI concerns
– Trackball = stationary upside-down mouse
• Touchpad
– When mice are impractical
– On laptops
8. Input Devices
• Bar code reader
– Reads bar codes – converts them to numbers
– Common in supermarkets, libraries, parts
warehouses etc
– Much faster and more accurate than hand-typing
product codes
9. Input Devices
• Touch screen
– Touch sensitive
– Tablet computers
– iPhone
– Railway ticket machines
– Information kiosks
– Bank ATMs
– Easy for public to use
– Can mimic any sort of
interface: buttons are only
images
10. Input Devices
• Data tablet
– Far better than a mouse for art
– Works like a pen
– Pressure-sensitive
11. Input Devices
• Scanner, digital camera
– Digitises analogue documents or pictures
– Scans page like a photocopier
– Use OCR (Optical Character Recognition) to interpret and
digitise printed text
– Resolution determines how detailed the resulting digital
image is.
• 1200 dpi resolution = 1200
dots per inch (2.54cm)
12. Output devices 1
Display the results of processing.
• Monitor
– CRT
– LCD, TFT
– Plasma
– Data projector
14. LCD monitors
• LCD = Liquid Crystal Display
• Thin, saves desk space
• Lighter than CRT
• Less power consumption than CRT
• Getting cheaper
• Refresh rates getting better
• Blacks often just grey
• Colour richness not as good as CRT
15. Data Projector
• Very portable
• Very large display
• Struggles in brightly lit rooms
• Colours are often dull
• Excellent for group presentations
• Lamps fail with age
18. Dot matrix printers
• The only printer type that strikes the paper…
• Only they can produce duplicates with
pressure-sensitive paper
• E.g. supermarket receipts - two or three
copies (white customer copy, yellow shop
copy) in only one print operation
19. Storage hardware
Stores & retrieves data and software.
• Hard disk
• Solid state disk
• Flash RAM, RAM, ROM
• CD, DVD
• Tape, floppy disk
20. Hard Disk Drive
• ‘HDD’
• Magnetic storage
• Multiple aluminium platters stacked on a
spindle
• Average HDD platters 3½” (inches)
• Laptop platters 2½”
• MP3 players 1”
21. USB Flash Drives
• NAND memory
• Normal RAM (Random Access Memory)
loses its memory contents when power is
turned off
• Normal ROM (Read Only Memory) has its
contents burnt at the factory and they
cannot be changed later
22. USB Flash drives
• Small, light, rugged (sealed, no moving parts)
• Cheap ones can be rather slow
• Typical capacity from 64M to 64G.
• Easily lost or left behind - possible security
issues
• Some USB Flash drives can be encrypted
23. CD, DVD
• Aluminium layer embedded in a 5¼”
polycarbonate plastic disc
• Laser burns data digitally as pits
• Data also read by laser beam
• Continuous, spiral data
track extends from innermost
to the outermost track, covering
the entire disc surface
24. CD, DVD
• Sensitive to scratches, heat
• Immune to magnetic effects
• Not “perpetual storage” as originally believed.
– Disks degrade over time, become unreadable
– Gold disks seem to last longer
The laser lens in
a CD drive
