computer tutorial part-2

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

04/10/2023 K. BARANIDHARAN.M.COM.,M.PHIL., M.B.A.,PH.D

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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


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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 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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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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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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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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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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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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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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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 PLOTTERSTHIS 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 USETHIS 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 record\infomation, 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

Date post:	23-Jan-2015
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computer tutorial part-2

Education