1. Introduction to Computers

2. M. Tawfiqul Islam, Lecturer, CSE, DU
Books
Introduction to Computer
Peter Norton
2. Computer Fundamentals
Dr. M Lutfar Rahman
3. Computer Fundamentals
Pradeep K. Sinha
M. Tawfiqul Islam, Lecturer, CSE, DU

3. M. Tawfiqul Islam, Lecturer, CSE, DU
Previous class
>>Organization of computer
Input Unit
Output Unit
Memory unit
Control Unit
ALU
M. Tawfiqul Islam, Lecturer, CSE, DU

4. Today’s Class

5. M. Tawfiqul Islam, Lecturer, CSE, DU
Output unit
>>Output Unit
Printer
Monitor
plotter
Speaker
Touch Screen
M. Tawfiqul Islam, Lecturer, CSE, DU

6. M. Tawfiqul Islam, Lecturer, CSE, DU
Printer
Two types- Impact & non-impact
Impacts are Type writers like dot matrix, line printer, drum printer
Non-impact printer works by creating images like ink jet printer, laser printer, photo printer, Thermal printers.
M. Tawfiqul Islam, Lecturer, CSE, DU

7. Dot matrix printer: Mechanism
Consists of print head which have a cluster (matrix) of short pins arranged in one or more columns
Receiving command from the CPU, the print head pushes the appropriate pins in and out of its cluster
M. Tawfiqul Islam, Lecturer, CSE, DU

8. Dot matrix printer: Mechanism
Clusters in various combination can create various alphanumeric characters
When pin is out of cluster, produced pin strike the ribbon and press ink on the paper
The more pin in the cluster then higher the resolution
M. Tawfiqul Islam, Lecturer, CSE, DU

9. M. Tawfiqul Islam, Lecturer, CSE, DU
Dot Matrix Printer
M. Tawfiqul Islam, Lecturer, CSE, DU

10. Dot matrix printer: Advantages
Can make carbon copies
Lowest print cost per page
Ink ribbon does not easily dry out
M. Tawfiqul Islam, Lecturer, CSE, DU

11. Dot matrix printer: Dis-advantages
Noise level is very high
Resolution is very low
Limited quality
Limited color performance
Low speed of printing
M. Tawfiqul Islam, Lecturer, CSE, DU

12. Laser printer: mechanism
It uses laser light for printing mechanism
Just as the electron gun in a monitor can target at any pixel, the Laser in a laser printer can aim at any point on the drum, cresting a electric charge
The laser reflecting from the scanning mirror moving through the ‘beam alignment lens’ falls on imaging drum
M. Tawfiqul Islam, Lecturer, CSE, DU

13. Laser printer: mechanism
Toner contains tiny particles of ink strikes to the drum in the places the laser has charged
Then with the pressure and heat, the toner is transferred off the drum onto the paper
The amount memory used, determines the speed of printing.
M. Tawfiqul Islam, Lecturer, CSE, DU

14. M. Tawfiqul Islam, Lecturer, CSE, DU
Laser Printer
M. Tawfiqul Islam, Lecturer, CSE, DU

15. Laser printer: Advantages
Very high speed
No irritating sound like dot matrix printer
Low noise level
Low maintaince requirements
High quality image
Excellent graphics quality
A variety type of size and qualities
Monochrome printing speed: 4-16 ppm
Resolution: 300, 600 dpi (high quality: dpi)
M. Tawfiqul Islam, Lecturer, CSE, DU

16. Laser printer: Dis-advantages
Printer is costly
Rough use can damage the lens and the mirror
Toner is costly and need to be changed after a thousand of page printed.
M. Tawfiqul Islam, Lecturer, CSE, DU

17. Ink jet printers: requirements
Requires the ink nozzle containing CMYK
CMYK (cyan-blue, magenta-red, yellow, black)
Also requires specially coated papers
M. Tawfiqul Islam, Lecturer, CSE, DU

18. Ink jet printers: Mechanism
Ink is exposed to UV radiation source where chemical reaction will take place
A shuttered mercury vapor lamp is on either side of print head & produces a great amount of heat to complete the curing process
UV do not evaporate rather cure
M. Tawfiqul Islam, Lecturer, CSE, DU

19. Ink jet printers: Mechanism
Monomers due to UV ray forms polymer resulting high molecule which sets as a image on paper or plastic
No material is removed that means 100% of delivered volume is used to provide colorization
M. Tawfiqul Islam, Lecturer, CSE, DU

20. M. Tawfiqul Islam, Lecturer, CSE, DU
Inkjet Printer
M. Tawfiqul Islam, Lecturer, CSE, DU

21. Ink jet printers: Advantages
Do not need warm up time
Noise level is very low i.e. almost quite
Print finer, smoother with high resolution
Instant dry saves time
Printing Speed: 2-4 ppm
Resolution: 300 dpi, 600 dpi
Cartridge are less costly (than toner)
Most uses separate color cartridge and a BW cartridge which saves ink.
M. Tawfiqul Islam, Lecturer, CSE, DU

22. Ink jet printers: Dis-advantages
Relatively slow printing
clogged jets when not used
Very narrow ink jet nozzle can coagulate with dry ink at the head
M. Tawfiqul Islam, Lecturer, CSE, DU

23. Output device: Monitor
Categories based on the prime hardware used
Cathode ray tube (CRT)
Ex- typical monitors with heavy weight
Flat-panel display
Ex- LCD, LED etc
M. Tawfiqul Islam, Lecturer, CSE, DU

24. Output device: Monitor
Categories based on the color display
Monochrome: One color on a black background
Grayscale: Shades of gray on a white or off-white background
Color: From 16 to 16 million unique colors
M. Tawfiqul Islam, Lecturer, CSE, DU

25. M. Tawfiqul Islam, Lecturer, CSE, DU
Other kinds of monitor
Paper-white display
Electroluminescent (ELD) display
Plasma/gas plasma display
M. Tawfiqul Islam, Lecturer, CSE, DU

26. Monitor : Phosphor dots
The only single unit dot which is responsible for the image display
There are ‘three types’ of phosphor dots they are red, green and blue i.e. RGB
M. Tawfiqul Islam, Lecturer, CSE, DU

27. M. Tawfiqul Islam, Lecturer, CSE, DU
Monitor : Pixel
Pixel, short for picture element, is the smallest number of phosphor dots that the electron gun inside the monitor can focus on {01M pixel= 01 Million pixels}
Three phosphor dots combine to form a single unit pixel 01
pixel
M. Tawfiqul Islam, Lecturer, CSE, DU

28. M. Tawfiqul Islam, Lecturer, CSE, DU
Resolution
The more you have pixels in your monitor you will be able to see the more clear and sharp image.
This sharpness is called resolution
For more resolution you must have more pixels per inch area on the monitor and minimum distance of dot pitch
M. Tawfiqul Islam, Lecturer, CSE, DU

29. Refresh rate & Dot pitch
Refresh rate: It is the number of times per second that the electron guns scan every pixel on the screen
Dot pitch: The distance between the same color phosphor dots of the pixel
M. Tawfiqul Islam, Lecturer, CSE, DU

30. M. Tawfiqul Islam, Lecturer, CSE, DU
Organization of (CRT)
Its main part is a ‘cathode ray tube’.
At its one end there is a source of high voltage.
There is a ‘magnetic coil/yolk’ ; which is used to control the flow of electron
At the back of the screen there are ‘phosphor dots’
M. Tawfiqul Islam, Lecturer, CSE, DU

31. M. Tawfiqul Islam, Lecturer, CSE, DU
Mechanism
Electron gun shoots streams of electrons at a high voltage towards the screen
Magnetic coil controls the flow of electrons
Phosphor dots on the back of the screen glow when the electron beam hit them
M. Tawfiqul Islam, Lecturer, CSE, DU

32. M. Tawfiqul Islam, Lecturer, CSE, DU
Mechanism : Scanning
Electron gun do not scan it randomly but in a designed fashion
The electron gun scans from left to right
Then from top to bottom
Refreshing every phosphor dot in a zigzag pattern
M. Tawfiqul Islam, Lecturer, CSE, DU

33. M. Tawfiqul Islam, Lecturer, CSE, DU
Mechanism : Scanning
left
right
top
bottom
Indicates pixel
M. Tawfiqul Islam, Lecturer, CSE, DU

34. Why TV is not used as monitor?
Television display contains resolution which is just a half of computer monitor. So it cannot show output of computer operation.
Resolution indicates the sharpness of an image determined by the number of pixels on the screen. TV contains only the half number of pixels than monitor, so the resolution
M. Tawfiqul Islam, Lecturer, CSE, DU

35. Advantages of CRT monitor
Refresh rate is high
Relatively low cost
Viewing angle is more i.e. can be seen from different angle
M. Tawfiqul Islam, Lecturer, CSE, DU

36. Disadvantages of CRT monitor
Large In size
Not portable
Requires a lot of power to run it
M. Tawfiqul Islam, Lecturer, CSE, DU

37. Advantages of FLAT PANEL(LCD) monitor
M. Tawfiqul Islam, Lecturer, CSE, DU

38. Advantages of FLAT PANEL(LCD) monitor
M. Tawfiqul Islam, Lecturer, CSE, DU

39. Advantages of FLAT PANEL(LCD) monitor
the pixels are addressed in rows and columns
The column and row wires attach to transistor switches, one for each pixel.
The one-way current passing characteristic of the transistor prevents the charge applied to the pixel from draining between refreshes to the display image
M. Tawfiqul Islam, Lecturer, CSE, DU

40. Advantages of FLAT PANEL(LCD) monitor
Small in size, small space requires
Portable as weight is less than CRT monitor
High resolution
A little power consumption
M. Tawfiqul Islam, Lecturer, CSE, DU

41. Advantages of FLAT PANEL(LCD) monitor
Small in size, small space requires
Portable as weight is less than CRT monitor
High resolution
A little power consumption
M. Tawfiqul Islam, Lecturer, CSE, DU

42. Disadvantages of FLAT PANEL(LCD) monitor
Low refresh rate
Viewing angle is low
Images can be difficult to see in bright light
M. Tawfiqul Islam, Lecturer, CSE, DU

43. M. Tawfiqul Islam, Lecturer, CSE, DU
Output unit: Speaker
Speaker is well known output device usually outputs sound
It is attached with the sound card of the computer
Sound can be controlled by controller
Electric signal is converted and it changes the air pressure outside which we call sound
M. Tawfiqul Islam, Lecturer, CSE, DU

44. M. Tawfiqul Islam, Lecturer, CSE, DU
How a Sound Card Works?
M. Tawfiqul Islam, Lecturer, CSE, DU

45. M. Tawfiqul Islam, Lecturer, CSE, DU
Output device: Touch screen
M. Tawfiqul Islam, Lecturer, CSE, DU

46. M. Tawfiqul Islam, Lecturer, CSE, DU
Output unit: Plotter
A output unit like printer used to print large size posters
Requires specified paper and ink
It takes a few hours to print the poster
M. Tawfiqul Islam, Lecturer, CSE, DU

47. M. Tawfiqul Islam, Lecturer, CSE, DU
Output unit: Plotter
M. Tawfiqul Islam, Lecturer, CSE, DU

48. Question...???