peripheral devices

1. Peripheral Devices

2. 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

3. 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.

4. Input Devices (1)
• Keyboard
• P/S2 keyboard
• USB keyboard
• Wireless keyboard

5. Input Devices (2)
• Pointing Devices
• Mouse, trackball, touch pad, light pen, digitizer
• Touch screen

6. 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)
• Optical mark scanner (OMR)

7. 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

8. Input Devices (5)
• Handwriting Recognition Device
• Need handwriting recognition software
• Called natural input
• Slow inputting speed

9. Output Devices (1)
• Visual Display Unit (VDU)
• Commonly called monitor
• 2 common types of monitor
• CRT (Cathode Ray Tube) monitor
• High radiation and bulky
• LCD (Liquid Crystal Display) monitor
• No radiation and slim

10. 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

11. 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

12. 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

13. 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)

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

15. Storage Devices (1)
• Floppy Disk (Diskette)
• A flexible plastic circular disc
• Packed in a plastic square jacket
• Formatted to 1.44MB
• Divided to many circular tracks
• Each track is divided to many sectors
• Use magnetic technology to store data ‘0’ or ‘1’
• Random access
• Slow accessing speed

16. Storage Devices (2)
• Hard Disk
• High storage capacity, over 100 GB
• Hard metallic surface
• Consists of several metallic disks
• Data are stored in cylinder (a deck of tracks)
(see p.86)
• Use magnetic technology
• Very high access speed
• Random access

17. 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
› Random access
› High access speed

18. Storage Device (4)
• Tape
• Cheap
• Sequential access
• Use magnetic technology
• Ideal for backup data, we need to backup and restore all
data
• 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.

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

20. 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
• Usually 100 MB/s
• Wireless LAN card
• Usually 11 MB/s
• Work within the distance range, and no blocking in between.

21. Network Devices (2)
• Connectors
• RJ-45 telephone jack connector
• For connecting twisted pairs LAN cable
• BNC connector
• For connecting coaxial cables

22. Network Device (3)
• Terminators
• Use in bus network, to prevent signal rebounce
and echo at the ends of bus.

23. 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.
• Router
• To connect different LANs together to form a Wide
Area Network (WAN)

24. Network Device (5)
• Repeater
• When a network spans a long distance, the signal
weaken, repeater is used to reproduce the signal.
• Exchange
• To boost the signals along the network path for a
Wide Area Network.

25. Network Device (6)
 Computer
› Different computers play different roles on a
network
 Server
› Provide services to other computers connected
to the network, usually have higher processing
power and larger storage capacity.
 Workstation
› The computers connected to the network but not
act as a server.

26. Network Device (7) - Servers
• File server
• control the sharing and access of files over the network,
must have a huge storage capacity.
• Print server
• Manage the print jobs from different computers to
different network printers, and manage the print queues.
• Web server
• To host a web site and publish web pages on the web,
support HTML, Java script, CGI, PHP and ASP web
languages
• Email server
• To store, send and receive emails over the Internet
• Internet server
• To provide Internet access

27. 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)

28. Data/Signal Rate
 Data Rate
› Refer to the no. of bits per second sent
 Signaling Rate (Baud Rate)
› Refer to the no. of signals per second sent
› Each signal may consists of several bits e.g. 101
 Bandwidth
› The frequency range of a particular media
› is directly proportional to the data rate

29. Types of network
• Client-Server Network
• Some computers act as server to provide services to
clients on the network
• Server programs are running on the server
• Client programs are running on client computers
• Peer-to-peer Network
• Every computer plays the same role in the network. They
form a workgroup, no server and no client
• The security in a peer-to-peer network is low.
• It is easy to set up, since no server programs or client
programs need to be run.