1. Introduction to Computing
Lecture-2-Input/ Output and Storage Devices
Muhammad Hafeez
Department of Computer Science
GC University Lahore

2. Today’s Agenda Input devices Understanding of Input devices
Output devices
Understanding of Output devices
Storage devices
Understanding of Storage devices

3. I/O Devices
Input/ Output devices commonly called I/O devices are used to interact the CPU with outside world
I/O devices also called peripheral devices

4. Types of Input Devices Keyboard Devices Point-and-Draw Devices
Mouse
Trackball
Joystick
Electronic Pen
Touch Screen

5. Types of Input Devices

6. Types of Input Devices

7. Types of Input Devices Data Scanning Devices Electronic-card Reader
Image Scanner
Optical Character Reader (OCR) devices
Optical Mark Reader (OMR)
Bar-Code Reader
Magnetic-Ink Character Recognition (MICR)
Digitizer
Electronic-card Reader
Speech Recognition System
Vision-Input System

8. Input Devices Keyboard: A 101-key QWERTY keyboard
Point-and-Draw Devices
When input medium shifted from text to GUI researchers find point-and-draw devices more convenient to point and icons and draw lines, curves on screen. Few point-and-draw devices are:
Mouse: A small pointing device fits in user palm. Most convenient and must have for today’s GUI interface
Mechanical and Optical Mouse
One, Two or Three Button Mouse
Wired or Cordless Mouse

9. Input Devices Point-and-Draw Devices
Trackball: Ball is moved with hand, device does not mode
Joystick: Used to play games, a stick is mounted on top of device
Electronic Pen
Touch Screen: A device provide input to the computer using touch of hand. Hand touch is monitored using sensors.
Information Kiosk
An unattended system at public place to help users.

10. Input Devices Point-and-Draw Devices
Trackball: Ball is moved with hand, device does not mode
Joystick: Used to play games, a stick is mounted on top of device
Electronic Pen
Touch Screen: A device provide input to the computer using touch of hand. Hand touch is monitored using sensors.
Information Kiosk
An unattended system at public place to help users such as ATM

11. Input Devices Data Scanning Devices
Input devices that enable direct entry into computer from documents
Eliminate the need of manual entry by human, reduce error in entry
Improve data accuracy and fast processing of information
Only high quality documents can be processed, however, work is in progress where lower quality documents can also be entered
Form design and ink selection becomes important

12. Input Devices Data Scanning Devices
Image Scanner: translate paper document into electronic format. Input paper may be text, image or picture. Useful for preserving documents. Scanned documents can be changed using image-processing software.
Flatbed scanner
Hand-held scanner
Limitations:
No word processing can be done.
More storage is required to store images than text and numbers

13. Input Devices Data Scanning Devices
Optical Character Recognition: The scanner is equipped with Character Recognition software called OCR s/w. It converts scanned document into equivalent ASCII characters. Scanner first read image then OCR software converts into character, numbers and special characters.
OCR software are complex, as the machine is limited to recognize characters, hence, special OCR fonts are used.

14. Input Devices Data Scanning Devices
Optical Mark Reader: A scanner that can recognize a pre-specified mark by pencil or pen.
Bar-Code Reader: A scanner used to read vertical lines on products called bars.
Convert bars into alpha-numeric values.
Universal Product Code UPC is widely used bar-coding system.
RFID: tagged devices, do not require direct or line-of-sight interaction

15. Ergonomics
An applied science devoted to incorporate comfort, efficiency and safety into design of items in workplace

16. Ergonomically Designed Workplace

17. Output
Information out of Computer System after processing the data is called output.
Output can be of the form:
Text
Graphics
Audio
Video
Also classified as:
Softcopy
Hardcopy

18. Output Devices Display Display Technologies: Flat panel display
LCD devices lit through backlight
Backlight source could be:
CCFL (Cold Cathode Fluorescent Lamp)
LED (Light Emitting Diodes)
LED is light, thinner, brighter but expensive
LCD produce color using active-matrix or TFT (thin-film transistor) a separate transistor for each liquid crystal cell, high quality video

19. Output Devices Display Display Technologies:
OLED (Organic LED) technology, organic molecules have the capability to not use backlight and lit themselves
Retina Display Technology or AMOLED (active matric OLED) used to view picture from various sides

20. Output Devices Display Display Quality: Resolution (1600x900)
Response Time (turn pixel on/off , 2-16ms)
Brightness (measured in nit)
Dot pitch (distance in mm between pixels, 0.3 mm)
Contrast ratio (difference in lightest white and darkest black, 500:1 to 2000:1, higher ratio represent better colors)

21. Output Devices Printer Impact Printers: Dot-Matrix
Non-Impact Printers: Ink-jet , Laser

22. Output Devices Laser Printer:
Combine a laser, high voltage, charged ions, powdered ink, heat and paper
A photo sensitive imaging drum “painted” with a laser
Laser prints character on drum
This drum also transfers toner to the paper

23. Output Devices Laser Printer:
Toner do not touch the paper, we have to use heat to make tiny particle of powder to produce characters on papers
A photo sensitive imaging drum “painted” with a laser
Laser prints character on drum
This drum also transfers toner to the paper
Speed: 4 to 50 ppm

24. Laser Printer

25. Laser Printer

26. Laser Printer

27. Laser Printer

28. Laser Printer

29. Ink-Jet Printers

30. Ink-Jet Printers

31. Impact Printers
Use mechanism to physically press ribbons on paper to create the desired character
Dot Matrix Printer

32. Dot Matrix Printer Printer characters a pattern of dots
Print many special characters and graphics
Can be used to generate multiple copies
Slow, 30 – 600 cps
Cheap in both, initial cost and cost of operation
Speed: 1 to 20 ppm

33. Questions
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