Input Output Devices and Physical Devices Used To

8/3/2019 Input Output Devices and Physical Devices Used To

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INPUT DEVICES

Entering data or instructions into a

computer is called input

An input device is a device which enters

data or instructions into a computer

It is necessary to convert data into a form

which can be understood by computers


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Some Input Devices are
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Some Input Devices are


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The Mouse

It controls the cursor on the screen

It has two or three buttons and a cable connecting it tothe computer

It is easy to operate

Once the cursor is at the desired location, the user cangive instructions to the computer by clicking the button
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The Joystick

A joystick looks like a stick fixed onto a box


It is alternate to the mouse
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The Keyboard

Keyboards come in different shapes and sizes

depending on the type of brand


It is alternate to the mouse
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The Scanner

This looks like a photocopying machine

Its function is to scan any document placed on itsflat glass

It sends the contents to the computer


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The Bar Code Reader

The black and white lines printed on certain

products which represent information like thecountry of origin, the price of it etc are bar codes

They can be read by a bar code reader which arecommonly used in Supermarkets and shops


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OUTPUT DEVICES

The information we get from the computer

is known as output

The computer presents this information

through these devices


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Some Output Devices are
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Some Output Devices are
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The Monitor

The monitor is one of the most important output

devices, it is used to display text and pictures

The monitor is also known as the Visual Display

Unit (VDU)


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The Printer

There are several types of printers, some are:

Dot matrix - Consists of a print head with a number ofpins which move in and out to print in the form of dots

Ink- jet - Consists of a print head with a number of tinynozzles and coloured ink to form tiny dots

Laser - Prints images by transferring ink powder onto apiece of paper using a laser beam
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The Plotter

A plotter produces its output using special pens

across the paper to create a drawing

Engineers, architects and designers use plotters toproduce their drawings or designs
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The Microfilm

The computer can also output its data on film

A microfilm is a film available in the form of reels

Large amounts of data can be stored this way
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PHYSICAL DEVICES USED TO

CONSTRUCT MEMORY

Memory Cell

A Capacitor Storage Cell

A Flip-Flop Storage Cell


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Memory Cell

Binary Cell can be placed in one or two stablestates

Two stable states are:-

(a) 1 State

(b) 0 State

Input line is to feed the data to be written

The data stored in the cell appears on theoutput line

When data is to be written, a signal is placed onwrite line

When data is to be read , a signal is placed onthe read line

If a 1 is to be written in a cell, voltagerepresenting a one is fed to the input line


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A Capacitor Storage Cell

A capacitance can be in twostates :-

(a) A state which is fullycharged i.e. 1 state

(b) Another which is fullydischarged i.e. 0 state

If a 1 is to be written in the

cell, a voltage V is to beapplied to the input line anda write signal is applied tothe write line.


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Advantages

Capacitor Storage Cell is inexpensive

The area required to fabricate a cell is very small


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Disadvantages

Capacitor Storage Cell is volatile

The read out from this cell is also destructive


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Uses

This storage cell is the one used to fabricate what isknown as Dynamic Random AccessMemory(DRAM)


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Advantages

It takes lesser time to store a bit in it

The data stored in a cell is not lost with passage oftime

The readout from a flip - flop is non - destructive


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Disadvantages

Flip-Flops are more expensive

It occupy more space as they use four switches

They need continuous application of power tomaintain their state when power fails the stored datais lost


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Uses

It is used to fabricate what is known as StaticRandom Access Memory(SRAM)

Documents

Input Output Devices and Physical Devices Used To