different devices of computer

1. Peripheral Devices

2. The Peripherals
• Peripherals connect to the computer input/output (I/O) ports
• They provide input or receiving its output
• They are not considered part of the computer:
– They are only specialized gadgets that encode or decode
information between the computer and the physical world

3. The Peripherals
The peripherals handle the physical part of the operation e.g:
 The keyboard encodes our keystrokes into binary form for the
computer
 The monitor decodes information from the computer’s memory and
displays it on a screen

4. A Device Driver for Every Peripheral
• Most peripheral devices are “dumb”
– They provide only basic physical translation to or from binary signals.
• Additional information from the computer is needed to make it operate
“intelligently”

5. A Device Driver for Every Peripheral
• Added processing by software called a device driver gives the peripheral
its standard meaning and behavior
• Every device needs a device driver

6. Device Drivers
 A program to tell the system software how to work with that piece of
hardware
 Some common device drivers are built in the system software (Operating
System) e.g. keyboard and mouse drives

7. Plug-n-Play Devices
 Devices designed such that Windows can detect them, install and
configure the device driver automatically
 For non plug-n-play devices, we have to install and configure the
device driver manually.

8. Types of Peripheral Devices
 Input Devices
 Output Devices
 Storage Devices
 Other Devices
– Network Devices
– Communication Devices

9. Basic Input Devices
 Keyboard
 Pointing device
– Mouse
– Pointing stick
– Trackpad/Trackball
– Joystick
 Touch screen

10. Input Devices (1)
 Keyboard
– P/S2 keyboard
– USB keyboard
– Wireless keyboard

11. Input Devices (2)
 Pointing Devices
– Mouse, trackball, touch pad,
– light pen
– Touch screen

12. Input Devices (3)
 Scanning devices
– Image scanner
– Fax machine – scan image to bitmap
– Bar code scanner – scan Universal Product Code (UPC)
– Magnetic ink character scanner (MICR)
– Optical character scanner (OCR)

13. Input Devices (4)
 Voice Input Device
– Microphone – to receive the sound signal
– Sound card – to convert the sound signal to digital form
– Use speech recognition software to recognize human speech

14. Input Devices (5)
 Handwriting Recognition Device
– Need handwriting recognition software
– Called natural input
– Slow inputting speed

15. Output Device

16. Output Devices (1)
 Visual Display Unit (VDU)
– Commonly called monitor
 3 common types of monitor
– CRT (Cathode Ray Tube) monitor
 High radiation and bulky
– LCD (Liquid Crystal Display) monitor
– LED (Light-Emitting Diodes
 No radiation and slim

17. 17
Display Devices
 A CRT display device uses a bulky glass tube
 An LCD manipulates light within a layer of liquid crystal cells
 Plasma screen technology illuminates lights arranged in a
panel-like screen

18. Output Devices (2)
 Printer – to produce hard copy
 Laser printer
– to produce high quality output
– resolution up to 2400 dpi (dot per inch)
– use carbon toner, usually for black and white printout, colour is very
expensive

19. Output Devices (3)
 Inkjet printer
– produce good quality colour output
– resolution up to 1440 dpi
– use ink droplets to compose the image
– The printer is much cheaper than laser printer but the ink is very expensive

20. Output Devices (4)
 Dot matrix printer
– Use impact principle
– Can print multiple (carbon) copies at a time, usually use in printing invoices
– The ink ribbon is cheap
– Poor quality of printout

21. Output Devices (5)
 Plotter
– Drawing high quality image, use colour pens, can draw smooth curves
– Can print on large paper size, use roll of paper
– To draw posters and maps
– Use in CAD (Computer Aided Design)

22. Output Device (6)
 Voice output devices
– Sound card, to convert computer signals to sound
– Speakers, to amplify the sound output

23. Storage Device

24. Portable Memory & Hard Drives
• Some peripherals are used by computers for both input and output:
– USB memory
– Hard disks/drives
• They are storage devices
• The hard disk is the alpha-peripheral, being the most tightly linked device
to the computer

25. Hard Disk
 Hard disk is essential
 Programs and their data must reside in the computer’s memory when
programs run
 The hard disk can be seen as an extension of the computer’s memory
 Typically it is a hundred times larger and several thousand times slower

26. Storage Devices (1)
 Floppy Disk (Diskette)
– A flexible plastic circular disc
– Packed in a plastic square jacket
– Formatted to 1.44MB
– Slow accessing speed

27. Storage Device (3)
 Optical disk
– CDROM, DVDROM, CDRW, DVDRW
– Use optical technology, laser reflection on pits
– ‘1’ will reflect the laser beam while ‘0’ does not
– High storage capacity, 700 MB for a CDROM, 17GB for a DVDROM
– High access speed

28. Storage Device (4)
 Tape
– Cheap
– Sequential access
– Use magnetic technology
– High storage capacity
– Slow access speed
– Group of records are stored in a block
– Inter-block gaps are needed for stopping and starting the read/write head.

29. Storage Device (5)
 Other Storage devices – can be read/write
 Removable disks -Zip disk(100/250MB), superdisk(120MB), Jazz
disk(1GB)
 USB (upto 32GB or even more
 Flash memory cards – compact flash, smart media and memory stick,
commonly used in digital camera

30. Other Peripheral Devices
 Network Devices
 Communication Devices

31. Network Devices (1)
 Network Interface Card (NIC) (LAN card)
– Connection between the network and the computer bus
– Have built-in transceiver, for data transmitting and receiving
– Can store in 1 GB/s
 Wireless LAN card
– Storage Capacity is in GB/s
– Work within the distance range, and no blocking in between.

32. Network Devices (2)
Connectors
 RJ-45 telephone jack connector
– For connecting twisted pairs LAN cable
 BNC connector
– For connecting coaxial cables
 Terminators
– Use in bus network, to prevent signal rebounce and echo at the ends of bus

33. Network Device (4)
 Hub
– To connect the workstations within a room on same floor
 Switch
– To connect the workstations for different floors in a building, it is faster and more
efficient than a Hub.

34. Network Device (5)
 Router
– To connect different LANs together to form a Wide Area Network (WAN)
 Repeater
– When a network spans a long distance, the signal weaken, repeater is used to
reproduce the signal.

35. Communication Device
 Modem - Modulator-demodulator
– It transforms digital signals of computer to analog signals to be transmitted through
telephone lines. (Modulation)
– It also transforms analog signals back to digital signals for the computer that
receives the signals. (Demodulation)