7. 7
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.
8. 8
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
9. 9
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
10. 11
Dot matrix printer: Advantages
• Can make carbon copies
• Lowest print cost per page
• Ink ribbon does not easily dry out
11. 12
Dot matrix printer: Dis-advantages
• Noise level is very high
• Resolution is very low
• Limited quality
• Limited color performance
• Low speed of printing
12. 13
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
13. 14
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.
14. 16
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: 1200-
1800dpi)
15. 17
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.
17. 19
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
18. 20
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
19. 22
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.
20. 23
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
21. 24
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
22. 25
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
23. 26
Other kinds of monitor
• Paper-white display
• Electroluminescent (ELD) display
• Plasma/gas plasma display
24. 27
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
25. 28
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
26. 29
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
27. 30
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
28. 31
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’
29. 32
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
30. 33
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
32. 35
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
33. 36
Advantages of CRT monitor
• Refresh rate is high
• Relatively low cost
• Viewing angle is more i.e. can be seen
from different angle
34. 37
Disadvantages of CRT monitor
• Large In size
• Not portable
• Requires a lot of power to run it
37. 40
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
38. 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
39. 42
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
40. 43
Disadvantages of FLAT PANEL(LCD) monitor
• Low refresh rate
• Viewing angle is low
• Images can be difficult to see in bright
light
41. 44
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
43. 47
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
46. 50
Memory
Memory:
– One or more set of chips that stores data or
programmed instructions either temporarily or
permanently.
Classification of memory:
1. Primary memory
2. Secondary memory
47. 51
Location of different memories
ALU
MAIN MEMORY
OR
RESISTERS
CONTROL
UNITINPUT
UNIT
OUTPUT
UNIT
SECONDARY MEMORY
48. 52
Calculations of storage capacity
01 BYTE (B) 08 bit
01KB 1024 B
01 MB 1024.1024 B
01 GB 1024.1024.1024 B
01 TB 1024.1024.1024.1024 B
50. 54
Memory Terminologies
• Memory Word:
– When memory is read or written, a
block of bit is read or written instead of
a single bit.
– The block is considered to be a unit of
operation/processing
– A set of bit with which read/write
operation is done in a certain storage
device is called memory word
– Example: 08 bits or 01 Byte memory
word clearly 01000000 (08 bits)
represents 64 and its character is @;
here, this digital 08 bits in combine
known as a memory word
100
B
X
Y
A
0000
0001
0002
FFFD
FFFE
FFFF
51. 55
Memory Terminologies
• Destructive:
– composed of capacitors, data disappears when
read operation is done, needs re-write
operation to retain data
• Non-destructive:
– reverse nature
– Example: semiconductor, switch, flash
memory, pen drive
52. 56
Memory Terminologies
• Volatile:
– Type of memory where data remains only
when the power supply is on.
– Ex-RAM
• Non-volatile:
– here content remains even the power is turned
off
– Example: hard disk, floppy disk, flash drive etc
53. 57
Memory Terminologies:
Memory operation
• Memory store/write:
– The process of storing or writing data at the
specific location of the memory
– Data is stored as bits
– Ex- CD writing operation
54. 58
Memory Terminologies:
Memory operation
• Memory read:
– Also called ‘fetch operation’
– To read stored data or to process that stored
data
– A binary word is selected from a specific
address of memory and this is transferred to
another device
– Example: To hear a song from CD or any drive
55. 59
Memory Terminologies:
Memory access
• Random access:
– Any location of storage can be accessed at
any moment
– Does not matter whether the desired access
location is too close or a far away
– Consumes almost same amount of time
– Found in primary and secondary memory
56. 60
Memory Terminologies:
Memory access
• Sequential:
– accessing a bit of information in a serial order,
one after another
– Access time depends on the last
order/information execution time
– Example: Off line storage such as playing a
song from magnetic tape
58. 62
Primary memory: RAM
• Central storage unit
• Volatile
• Temporary in nature
• Holds operating systems, application
programme, data in current use
• Other name is (Read/Write) memory
59. 63
Different types of RAM
• S RAM- Exhibits data remanance but still
volatile as data dissolves when turn off
• D RAM- Data disappears after a certain
period automatically if it is not refreshed.
This type of RAM needs periodically re-
read or re-written. Ex- Z-RAM, TT-RAM,
A-RAM
60. 64
Primary memory: ROM
• Proportionally read operation is more than write
operation
• Contains user programmed instructions like
Bootstrap loader
• Non-volatile
• permanent
62. 66
Secondary memory
• Auxiliary unit
• Storing capacity is huge
• Normally non-volatile
• Normally two types-
1. Magnetic
2. Optical
63. 67
Secondary memory: Magnetic
• Variation of ‘Magnet polarity’ determines
whether the bit will be 0 or 1
• Data write process is done by
electromagnetic head
• Ex- hard disk, floppy disk, magnetic tape
64. 68
Secondary memory: Optical
• Variation of light reflection determines the
nature of bits
• Data is written with the help of LASER or
UV rays
• Ex-CD-R/RW, DVD-R/RW, BD-R
65. 69
Memory address:
• It is a number or a set of digital number
(bit/Bytes) in the memory
• This address specially represented by
binary numbers
• Decimal, Octal, Hex-decimal numbers are
also used for addressing
66. 70
Virtual memory:
• When secondary memory is used as primary
memory then this is called virtual
• Provide assistance to the RAM, by creating
space for the great amount of data
• When RAM finishes it’s access, virtual memory
vanishes
• Virtual memory can be selected by user
67. 71
Cache memory:
• Small memory chip is attached between
CPU & main memory
• Give the assistance to the resisters
• Speed up the data process
• Three types of cache memory is found e.g.
L1(CPU resident), L2 & L3 (mother board)
68. 72
Resisters
• They are not the part of main memory but
store data and pass as directed by CPU
• The size of the resisters which is
sometimes called the word size,indicates
the amount of data with which CPU can
work/access.
• Ex- 32 bits processor means, 04 bytes
data processing capability