computer tutorials part - 2

8/8/2019 computer tutorials part - 2

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COMPUTER - 2

K. BARANIDHARAN.M.COM.,M.B.A.,M.PHIL.,PH.D.,

[email protected]@gmail.com


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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


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SCANNERS Scanners is an instrument which is used to scan a

diagram, photograph etc., and image can be broughton to the monitor.

The scanner is used light is ON in the scanner,appears on the screen of the monitor, this image canbe edited and shaped into desired from

To use a scanner, a special software is required to beloaded in the computer , the software is generallyavailable 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 photographsof the customers

23-11-2010 K. BARANIDHARAN.M.COM.,M.PHIL.,M.B.A.,PH.D

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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 andoutput 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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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 useRIBBON/CARBON papers to leave an impression on the paper

2. NON IMPACT PRINTER


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Impact

DOT MATRIX PRINTR

The impression of character in the form of DOTS/ahammer 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 printone line at one time/speed of line printers Ismeasured in terms of printing of lines perminute/work on large amount of data printing fora quite longer duration of time

The speed of line printer is wonderful and theycan print 300 to 2500 lines in a minute/the widthof 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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DAISY WHEEL PRINTER

This printer contains a disk of metal or plasticand it has 96 characters on its petals /this disk

is capable of rotating/the hammer of this

printer pushes the character and it leaves animpression of the alphabet on the paper

The typical speed of printer is 20 characters per

second to 100 characters per second/cannot beused for longer duration and slow

functioning/superior quality


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Non-impact

LASER PRINTR

The printers generate both graphics as well as textas 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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THERMAL MATRIX PRINTER

the printers work on heating arrangement,

special type of paper is needed for printing

it contains print wires and when electricity ispassed 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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INK JET PRINTER

The printer do not make a noise whileprinting/the drops of ink appear in the from ofcharacter/small pumps release tiny drops of inkthough nozzles onto the paper in the form ofcharacter

The printing of this printer is good and a goodquality 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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PLOTTERS

Plotters are output devices and are used forvarious purposes like graphics, diagrams etc

Three are different types of plotters and areused for various purposes

1. GRAPH PLOTTER

2. FLAT BED PLOTTER3. DRUM PLOTTER


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GRAPH PLOTTERS

AS EVIDENT FROM ITS NAME, GRAPHPLOTTERS ARE USED IN GRAPHIC WORKANDDIAGRAMS

FLAT BED PLOTTERSTHIS PLOTTER USES ALIGHT PEN AND DRAW GRAPHS ON THEPAPERS/MULTICOLORED PENS ARE USED FOR GRAPHICS/PENIS CONTROLLED BY PEN HOLDER, 8-10 COLOURS ARE USE

THIS PLOTTER IS ALO KNOWN AS light pen plotter IT CANMAKE GRAPHS OF SMALL TO LARGE SIZE DEPENDING UPONTHE SIZE BED


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DRUM PLOTTER

DRUM PLOTTER (PRINTR) CONTAINS A DRUMWHICH IS CYLINDRICAL IN SHAPE/DRUM ISCAPABLE OF ROTAING

DRUM PLOTTER PLOTS THE GRAPHS ON PAPERBY RORATING

NORMALLY A LINE IN PRINTED OUT PUTCONTAINS 132 CHARACTERS AND THIS CAN

PRINT 600-2000 LINES PER MINUTE

THESE PLOTTERS ARE VERY CONSTLY AND ARENOT 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, speechsynthesizer,etc.,

The keyboard enter the data into the computer and theCRT 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 andhelps 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 thecomputer

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, controlsthe 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 sameback 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 incase 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 LOGICUNIT.

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 hepower 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 powersupply 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 requiredrecord/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 record\infomation, we have not to pass though the

remaining data/magnetic disks store the data on to them in directaccess 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 thememory 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 tutorials part - 2