Peripheral devices connect to computers through input/output ports and provide input or output. They include input devices like keyboards and mice, output devices like monitors and printers, and storage devices like hard drives and flash drives. Device drivers are software that allow the operating system to communicate with peripherals and give them standard behaviors. Common peripherals include keyboards, mice, monitors, printers, hard drives, network cards, and modems.

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)