computer tutorial part-2

COMPUTER - 2
K. BARANIDHARAN.M.COM.,M.B.A.,M.PHIL.,PH.D.,
baranibarani50@yahoo.com
dharanbarani21@gmail.com

FLOPPY DISK
• Floppy disk is a recent development in storge devices – it was developed
in 70s
• This is very small storage device which can be used both as input and
output medium – this is made up elastic plastic material and a finely
coated with magnetic oxide
• This disk is placed in plastic cover to avoid damage – the floppy is
avaiable in 3 standard size of, storage capacity
– 8 inches - 250 KB to 1.5 MB
– 5.25 inches - 125 KB to 1 MB
– 3.5 inches - 720 KB to 1.44 MB ==FEATURES===
• It is small storage medium-easily taken from one place to another place-
cheap storage medium-very useful for PV-both input and output device-
reading and writing-small commercial houses
• The floppy is inserted into floppy drive-this rotates inside the floppy drive
like a musical record and the data is stored on fine circular paths called
tracks

SCANNERS
• Scanners is an instrument which is used to scan a
diagram, photograph etc., and image can be brought
on to the monitor.
• The scanner is used light is ON in the scanner,
appears on the screen of the monitor, this image can
be edited and shaped into desired from
• To use a scanner, a special software is required to be
loaded in the computer , the software is generally
available with the scanner
• Optical scanners are becoming very popular for the
purpose of office automation
• Now-a-days, computerised bank branches are using
scanners for storing the signatures and photographs
of the customers
29-01-2015
K. BARANIDHARAN.M.COM.,M.PHIL.,
M.B.A.,PH.D
3

OUTPUT UNITS
• the function of output units is reverse in nature than that of input
unit /input unit is used to fee the data into the computer and
output unit takes out of the data from the computer-the following
are some devices which are used as output devices:
• MAGNETIC TAPE FLOPPY DISK
• DAISY WHEEL PRINTER DOT MATRIX PRINTER
• LASER PRINTER LINE PRINTER
• OPTICAL PRINTER VED DISPLAY UNIT(vdu)
• MICROFILM MICROFICHE
• TAPES PLOTTERS
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M.B.A.,PH.D
4

PRINTERS• Printers are the output devices
• The data/information from the main memory of computer is transferred
to the memory of printer and the same is printed in the form of output.
• The data can be printed in the form of graphs, letters, reports etc. as
desired by the user
– As shown in the figure, the printers are mainly divided into two parts
1. IMPACT PRINTER = Impact printers use
RIBBON/CARBON papers to leave an impression on the paper
2. NON – IMPACT PRINTER
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5

Impact
DOT MATRIX PRINTR
• The impression of character in the form of DOTS/a
hammer which prints the characters one by
one/the output obtained in he form of DOTS/the
hammer of head contains 9 pins or 24 pins
• The typical speed of dot matrix printer is 40
characters per second to 1000 characters per
second
• The printer mostly print in left to right movement
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LINE PRINTER
• Line printers are called so because these print
one line at one time/speed of line printers Is
measured in terms of printing of lines per
minute/work on large amount of data printing for
a quite longer duration of time
• The speed of line printer is wonderful and they
can print 300 to 2500 lines in a minute/the width
of the line is 15 inches and the line has 96 to 160
characters
• Chain printers and drum printers come in the
category of line printers
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CHAING PRINTERS
• In a chain printer, a chain of characters rotates
and in this process hammer of the printer
strikes on chain and the character of the chain
leaves an impression of the character on the
paper
• This printer can work for a longer time but the
quality of output is not so good
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8

DAISY WHEEL PRINTER
• This printer contains a disk of metal or plastic
and it has 96 characters on its petals /this disk
is capable of rotating/the hammer of this
printer pushes the character and it leaves an
impression of the alphabet on the paper
• The typical speed of printer is 20 characters per
second to 100 characters per second/cannot be
used for longer duration and slow
functioning/superior quality
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9

Non-impact
LASER PRINTR
• The printers generate both graphics as well as text
as image output and is very good, use the
technique of laser and photocopy
• The speed of this printer is marvelous, print more
than 300 pages in one minute/now ,can print
multicoloured graphis/output
• As the quality of the output is very good, laser
printers are used in Desk Top Publishing
• Limitations is very costly
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M.B.A.,PH.D
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THERMAL MATRIX PRINTER
• the printers work on heating arrangement,
special type of paper is needed for printing
• it contains print wires and when electricity is
passed through these wires and with passage
of current, the wires get heated and leave
impression with the help of special type of
ribbon
• these printers are slow and costly
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11

INK JET PRINTER
• The printer do not make a noise while
printing/the drops of ink appear in the from of
character/small pumps release tiny drops of ink
though nozzles onto the paper in the form of
character
• The printing of this printer is good and a good
quality of graphics can be obtained/speed of ink
jet printer ranges between 50-300 characters per
second
• The shaped of these printers is very less as
compared to laser printers
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M.B.A.,PH.D
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PLOTTERS
• Plotters are output devices and are used for
various purposes like graphics, diagrams etc
• Three are different types of plotters and are
used for various purposes
–1. GRAPH PLOTTER
–2. FLAT BED PLOTTER
–3. DRUM PLOTTER
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GRAPH PLOTTERS
• AS EVIDENT FROM ITS NAME, GRAPH
PLOTTERS ARE USED IN GRAPHIC WORK
ANDDIAGRAMS
FLAT BED PLOTTERS
THIS PLOTTER USES ALIGHT PEN AND DRAW GRAPHS ON THE
PAPERS/MULTICOLORED PENS ARE USED FOR GRAPHICS/PEN
IS CONTROLLED BY PEN HOLDER, 8-10 COLOURS ARE USE
THIS PLOTTER IS ALO KNOWN AS light pen plotter IT CAN
MAKE GRAPHS OF SMALL TO LARGE SIZE DEPENDING UPON
THE SIZE BED
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DRUM PLOTTER
• DRUM PLOTTER (PRINTR) CONTAINS A DRUM
WHICH IS CYLINDRICAL IN SHAPE/DRUM IS
CAPABLE OF ROTAING
• DRUM PLOTTER PLOTS THE GRAPHS ON PAPER
BY RORATING
• NORMALLY A LINE IN PRINTED OUT PUT
CONTAINS 132 CHARACTERS AND THIS CAN
PRINT 600-2000 LINES PER MINUTE
• THESE PLOTTERS ARE VERY CONSTLY AND ARE
NOT USED WIDELY
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Visual Display Units(VDU)
• Model of TV, displayed by Cathode Ray Tube to display a
data, graphics, letters, pictures etc.,/common output
device besides printer, plotter, speaker, speech
synthesizer,etc.,
• The keyboard enter the data into the computer and the
CRT is used to display the input data as well as the
messages and processed out put from the computer
• The CRT produces a beam of electrons that makes the
picture on the screen/the raster scan in the VDU and
helps to convert the beam into a picture
• Graphic capacities depend on the capacity of the adapter
• Monochrome and coloured monitors are the two types
of monitors
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CENTRAL PROCESSING UNIT (CPU)
• CPU is the main part of the computer
• In other words it is referred to as BRAIN of the computer
• This part of the computer controls all the functions of the
computer
• CPU divided into THREE parts
–CONTROL UNIT
–ARITHMETICL LOGIC UNIT
(ALU)
–MEMORY UNIT
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CONTROL UNIT
• Control unit, as a evident from the name, controls
the working of the computer and ascertains
whether the computer is functioning as per the
commands given to it by the user or not
• This part is located between MEMORY UNIT
and ARITHMETICAL LOGIC UNIT
• The data can be transferred between them
though this unit
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ARITHMETICL LOGIC
• The function of this unit is to verify
the accuracy of data received from
memory unit and transfers the same
back to the main memory of the
computer
• This part performs all arithmetical
and logical functions
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MEMORY UNIT• This unit stores data, calculations and results into it and in
case of need it sends the data in the form of output
• the capacity of memory is measured in terms of BYTES,
KILOBYTES or MEGABYTES / the bigger unit is GIGA BYTE
• Memory unit transfers the data to ARITHMETICAL and LOGIC
UNIT.
• 1 KB = 1024 BYTES
• 1 MB = 1024 X 1024 BYTES
• 1 GB = 1024 X 1024 X 1024 BYTES
• 1 TERA BYTE = 1024 X 1024 X 1024 X 1024 BYTES
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VOLATILE
• Memory may be volatile or non-volatile in
nature
• Volatile memory is washed a soon as he
power is cut
• The informations and the data is also washed
as soon as the power supply is stopped
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NON-VOLATILE
• Non-volatile memory is not washed if the power
supply is cut and hence the data and
informations are safe in that memory, mainly
memory of computer is of following types:
• 1.Read Only Memory (ROM)
• 2.Random Access Memory (RAM)
• 3.Programmable Read Only Memory (PROM)
• 4.Erasable Programmable Read Only Memory (EPROM)
• 5.Electronically Erasable Programmable Read Only
Memory (EEPROM)
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• READ ONLY MEMORY
• This memory is also termed as FIRMWARE/this memory cannot be altered or
washed and permanent in nature/this memory gives instructions to the
compUter/ROM is non-volatile in nature
• RANDOM ACCESS MEMORY
• memory is temporary/washed as soon as the supply of power is cut/capacity of
computer is related with RAM/more powerful is computer = further divided
into 3 parts = 1.Cyclic 2.Serial Access 3.Direct :-
• 1.CYCLIC MEMORY:=this memory of the computer transfers the data in cyclic
order/this memory takes more time in transferring the data/the storage devices
like magnetic drums fall in this category
• 2.SERIAL ACCESS MEMORY:=this memory transfers the data in a serial order/the
data or records are read one by one/hence to reach a required
record/information, we have to pass through the remaining data/this memory
also takes more time in transferring the data and hence more time is wasted in
reading the required data/magnetic tapes store the data on to them in serial
access manner
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• 3.DIRECT ACCESS MEMORY:=this memory transfers the data in a
direct order and the time in reading the data is less/to read a
particular recordinfomation, we have not to pass though the
remaining data/magnetic disks store the data on to them in direct
access manner
• PROGRAMMABLE READ ONLY MEMORY
• this is a type of semi conductor chip on which program can be written
once and only once/this program is written with the help of computer
• ERASABLE PROGRAMMABLE READ ONLY MEMORY
• this is type of semi conductor chip on which the memory can be erased
with the exposure to ultraviolet radiations
• ELECTRONICALLY ERASABLE PROGRAMMABLE READ
ONLY MEMORY:=there are some special chips in the computer the
memory on which can be reprogrammed with the help of electronic
signals/the old data can be a newer one
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The following are some important devices which are used for
memory(data storage):=
Magnetic tables/disks/floppy disk/winchester disks/magnetic
drums
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computer tutorial part-2

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computer tutorial part-2