lec 5 output unit

WELCOME

MIS – 104:

Computing Fundamentals

BBA Department of MISUniversity of Dhaka

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Books

1. Introduction to Computer Peter Norton

2. Computer Fundamentals Dr. M Lutfar Rahman

3. Computer Fundamentals Pradeep K. Sinha

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Previous class

>>Organization of computerInput UnitOutput UnitMemory unitControl UnitALU

Today’s Class

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Output unit

>>Output UnitPrinterMonitorplotterSpeaker

Touch Screen

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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.

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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

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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

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Dot matrix printer: Advantages

• Can make carbon copies

• Lowest print cost per page

• Ink ribbon does not easily dry out

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Dot matrix printer: Dis-advantages

• Noise level is very high

• Resolution is very low

• Limited quality

• Limited color performance

• Low speed of printing

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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

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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.

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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)

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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.

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Ink jet printers: requirements

• Requires the ink nozzle containing CMYK • CMYK (cyan-blue, magenta-red, yellow,

black)

• Also requires specially coated papers

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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

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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

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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.

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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

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Output device: Monitor

• Categories based on the prime hardware used

• Cathode ray tube (CRT)Ex- typical monitors with heavy weight

• Flat-panel displayEx- LCD, LED etc

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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

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Other kinds of monitor

• Paper-white display

• Electroluminescent (ELD) display

• Plasma/gas plasma display

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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

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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

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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

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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

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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’

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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

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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

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Mechanism : Scanning

left right

top

bottom

Indicates pixel

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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

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Advantages of CRT monitor

• Refresh rate is high

• Relatively low cost

• Viewing angle is more i.e. can be seen from different angle

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Disadvantages of CRT monitor

• Large In size

• Not portable

• Requires a lot of power to run it

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Advantages of FLAT PANEL(LCD) monitor

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• 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

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• Small in size, small space requires

• Portable as weight is less than CRT monitor

• High resolution

• A little power consumption

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• Small in size, small space requires

• Portable as weight is less than CRT monitor

• High resolution

• A little power consumption

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Disadvantages of FLAT PANEL(LCD) monitor

• Low refresh rate

• Viewing angle is low

• Images can be difficult to see in bright light

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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

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Output device: Touch screen

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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

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Output unit: Plotter

Memory Unit

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Memory

Memory: – One or more set of chips that stores data or

programmed instructions either temporarily or permanently.

Classification of memory:1. Primary memory2. Secondary memory

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Location of different memories

ALU

MAIN MEMORYOR

RESISTERS

CONTROL UNITINPUT

UNITOUTPUT

UNIT

SECONDARY MEMORY

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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

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Memory Terminologies

• Memory Address:– Memory locations are

identified by numbers 100

B

X

Y

A0000

0001

0002

FFFD

FFFE

FFFF

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• 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

A0000

0001

0002

FFFD

FFFE

FFFF

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• 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

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• 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

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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

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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

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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

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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

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Primary memory

• Includes RAM & ROM

• CPU access directly on this memory

• Normally volatile in nature

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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

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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

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Primary memory: ROM

• Proportionally read operation is more than write operation

• Contains user programmed instructions like Bootstrap loader

• Non-volatile

• permanent

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Different types of ROM

ROM

M ROM M ROM M ROM M ROM

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Secondary memory

• Auxiliary unit• Storing capacity is huge• Normally non-volatile

• Normally two types-1. Magnetic 2. Optical

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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

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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

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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

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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

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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)

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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

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