info of peripherals

8/7/2019 info of peripherals

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4.Multimedia and Gaming KeyboardsThe multimedia and gaming keyboards are designed for playing audio and has hot-keys

for volume control, play, stop and mute operations. The gaming keyboards are designedfor the convenience of the gamers and these types of keyboards provide the required

controls on the keyboards like backlighting.

5.Virtual KeyboardsThe virtual keyboards are not actually physical keyboards, but they are simulated using a

software. Usually, the virtual keyboards are used in the PDA.

Working of Keyboard:

Whenever a key is pressed, a specific signal is transmitted to the computer. The keyboard

uses a crossbar network to identify every key based on its row and column

When a key is pressed, an electrical contact is formed between the row and column. Theelectric signals are transmitted to a microcontroller, which sends a code (BCD, ASCII orUnicode) to the computer describing the character which corresponds to that key.

Computer keyboard key:

F1 - F12 Information about the F1 through F12 keyboard keys.Tab Tab key

Capslock Caps lock key

Shift Shift keyCtrl Ctrl key

Alt Alt key (PC Only; Mac users have Option key)

Back Space Back space key
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Delete Delete or Del keyEnter Enter key

Printer:-

A printer is a device that accepts text and graphic output from a computer and

transfers the information to paper, usually to standard size sheets of paper. Printers aresometimes sold with computers, but more frequently are purchased separately. Printers

vary in size, speed, sophistication, and cost. In general, more expensive printers are used

for higher-resolution color printing.

OR

A printer is an output device that produces text and graphics on paper.

Types of Printer:-

DOT Matrix PrinterInkjet Printer

Laser Printer

PlottersThermal printerLED/LCD printers

Working of Printers:

1. Ink-jets(bubble-jets) printers:-Printer developed by Canon which forms letters andimages on the paper by spraying small streams of quick-drying ink. The ink is storedin a disposable ink cartridge.

2. Laser printers:-Laser printers are Printer that uses laser technology to print imageson the paper. The laser recreates the image on a negatively charged drum which will

then collect ink that is positively charged to attract to the areas of the image.

3. LED/LCD printers :-are types of electro photographic printers that are identical to

laser printers in most ways. Both LCD (liquid crystal display) and LED (light-emitting

diode) printers use a light source instead of a laser to create an image on a drum. Inmost contexts, "laser printer" covers LCD and LED printers as w
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4. DOT Matrix Printer: - Type of printer that employs movable print heads

with

pins or wires that shoot and strike the ribbon placing a dot on the paper with

hundreds of dots forming images or text.

5. Plotters :- These printers use a pen to draw the image on the paper. Usually,

plotters

are Friction Feed but occasionally can be Tractor Feed as well.

6. Thermal printer :- A printer that uses heated pins to "burn" images onto heat-

sensitive paper. The pins are electrically heated and brought into contact with the

specially treated paper easily, instead of with great impact. The coating on the

paper

discolors when heated in this way.

Mouse:-

- A device that controls the movement of the cursororpointeron a display screen.

A mouse is a small object you can roll along a hard, flat surface. Its name is

derived from its shape, which looks a bit like a mouse, its connecting wire that

one can imagine to be the mouse's tail, and the fact that one must make it scurry

along a surface. As you move the mouse, the pointer on the display screen moves

in the same direction.

Types of Mouse:

- Mechanical mouse

- Optical mouse

- Infrared (IR) or radio frequency cordless mouse- A mouse with many buttons

- Trackball mouse

- Stylus mouse

- Cordless 3-D mouse

Mechanical mouse: Houses a hard rubber ball that rolls as the mouse is

moved. Sensors inside the mouse body detect the movement and translate it

into information that the computer interprets.

Optical mouse: Uses an LED sensor to detect tabletop movement and then

sends off that information to the computer for merry munching.
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Infrared (IR) or radio frequency cordless mouse: With both these types,

the mouse relays a signal to a base station wired to the computer's mouse port.

The cordless mouse requires power, which comes in the form of batteries.

A mouse with many buttons: The extra buttons can be programmed to do

specific things, such as navigate the Web or turn pages when youre reading a

document. The typical button-ified mouse has about five buttons.

Trackball mouse: Like an upside-down mouse. Rather than roll the mouse

around, you use your thumb or index finger to roll a ball on top of the mouse.

The whole contraption stays stationary, so it doesnt need a lot of room, and

its cord never gets tangled.

Stylus mouse: Another mouse mutation enjoyed by the artistic type is the

stylus mouse, which looks like a pen and draws on a special pad.

Cordless 3-D mouse: This kind of mouse can be pointed at the computer

screen like a TV remote.

Mouse Functions

Action Result

Click Left mouse button moves the cursor, highlights an object, pullsdown a menu, or chooses a menu command

Right mouse button displays a shortcut pop-up menu

Double click Left mouse button highlights a word or edits an embeddedobject

Drag Left mouse button moves an object, resizes an object,highlights test, or highlights multiple objects

Highlight By use of the left mouse button, you can drag the cursor overword, paragraphs, or pages.

Triple click Left mouse button - Highlights a paragraph

Moniter:

A computermonitor is an electronic device that shows pictures. A

monitor is usually used to see programs on a computer. The main difference

between a monitor and a television is that a monitor does not have a television

tunerto change channels. A monitor may be used to watch television if it isconnected to a device that has a television tuner. Some models of monitor can be

used as a television, and some televisions are used with computers. A monitor has

a betterdisplay resolution than a television to make it easier to see smaller letters

and graphics on.
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Types of monitors:

The CRT monitor: which is big and heavy. It is the oldest technology used

by monitors. It looks like a television, but has a biggerdisplay resolution and

often a higherfrequency. CRT stands for cathode-ray tube.

The LCD monitor, :which is thin, flat, and lightweight. It is a newer

technology than CRTs. The quality can be the same or even better than a

CRT, but this type of monitor usually costs more than a CRT.

Cathode Ray Tube Monitors (CRT): The Cathode Ray Tube Monitors are

the types of monitors that were used in many personal computers for the past

many years. This is the conventional type of monitors that are used to view

the computer data.

Liquid Crystal Display (LCD) Monitors: The Liquid Crystal Display as the

name indicates has a wonderful display that is very good to look at because of

the very high resolution that is present on the screen.

The TFT screen: The thin film transistor or the TFT screen is commonly

used interchangeably with the Liquid Crystal Display (LCD) Monitors, but

there is a difference between the two.

Scanner:-

A scanner is a device that captures images from photographic prints, posters,

magazine pages, and similar sources for computer editing and display.A

computer scanner optically scans an object such as a document and converts theinformation into a digital image. Every scanner has a variety of specifications,

including resolution, color depth and speed.

Types of Scanners:

Flatbed Scanner

A flatbed scanner is made up of a glass pane and a moving optical CIS or

CCD array. The pane is illuminated with the help of bright light planted

underneath it.

Sheetfed Scanner

In sheetfed scanners, the document that is supposed to be scanned is fed into

the horizontal or vertical slot provided in the scanner. The vital components of

sheetfed scanner are the sheet-feeder, scanning module and calibration sheet.
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Handheld Scanner

A handheld scanner is a small manual scanning device which is moved over

the object that need to be scanned. For instance, if a document needs to be

scanned, the handheld scanner has to be dragged over the document

Photo Scanner

Photo scanners are mostly used to scan photographs. High resolution and

color depth are the most vital requirements for scanning photographs, and

photo scanner provides the same.

Film Scanner

A film scanner is utilized to scan photographic films directly into a computer.

The photographer has direct control over certain aspects, such as cropping,

ratio original image on the film, etc.

Applications of Scanner

1. Applications vary according to the type of scannerused. Flatbed scanners are

mostly used for scanning documents. But, for large format documents a

mechanical scanner will have to be used.

2. Scanners also find high end application in field like bio-medical research.

High resolution scanners with a resolution of almost 1 m/ pixel are used to

detect DNA microarrays. Here also, the charge coupled devices are used for

detection.

Working of Flatbed Scanner

The main difference in the old scanners and modern scanners is the type of image

sensor used. In old scanners, a photomultiplier tube [PMT] was used. For modern

scanners a Charge-coupled device [CCD] is used. A CCD sensor is used to capture

the light from the scanner and then convert it into the proportional electrons.

Work a scanner to convert a hard copy or document into a digital image that can be

viewed, manipulated or transmitted from a computer. It's very common for artists to

scan images created by hand into a computer. Scanning sketches is one way

cartoonists create computer-assisted animation. Scanners can also convert photos,

slides and film into digital frames. Documents also scan for digital reproduction

Modem:-

Modem is actually an odd acronym for Modulator-Demodulator. A modem takes a

digital signal from your computer and converts to an analog signal so that it can be

transferred through a phone line. This conversion is necessary because modems make

use of regular phone lines which are analog. Newer technologies don't require this

conversion, but more often than not, the term modem is still used.


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Types of Modem:

Internal computer modems:- An internal modem is a device installed inside

a desktop or laptop computer, allowing the computer to communicate over a

network with other connected computers.

dial-up and WiFi (wireless):- The former operates over a telephone line

and requires a network access phone number and logon credentials to make a

connection. Some computers have an internal modem which can be a built-in

modem or a PC card modem.

External modems:- An External modem can be used to the same purpose and

in the same conditions as internal computer modem. However external

modem is a small box that uses other kind of interfaces to be connected to the

computer.

Cable modem:- The cable modem uses a coaxial cable television lines to

provide a greater bandwidth than the dial-up comuter modem. An extremely

fast access to the Web is providing by the cable modem with downstream

transmission up to 38 Mbits/s and an upstream transmission up to 1 Mbits/s.

DSL modem:- DSL (Digital Subscriber Line) modem is exclusively used forconnections from a telephone switching office to the user. DSL modem is a

device used to connect a single computer or router to a DSL phone line, in

order to use an ADSL service.

Working of Modem:

A computer sends information in the form of digital signals. But the information over

the telephone lines needs to be transmitted in the form of analog signals. To solve this

problem, the functionality of a modem comes into play. It converts the digital signals

into analog signals. These analog signals are carried over the telephone lines. When

these signals reach another computer, the analog signals are converted back to the

digital form by its modem.

Functions of the Modem:

Error Correction:- In this process the modem checks if the information they

receive is undamaged. The modems involved in error correction divide the

information into packets called frames

Compressing the Data: For compressing the data, it is sent together in many

bits. The bits are grouped together by the modem, in order to compress them.


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Flow Control: Different modems vary in their speed of sending signals. Thus,

it creates problems in receiving the signals if either one of the modems is

slow.

CD Drive:compact disc (CD), a small plastic disc used for the storage of digital data.a

drive that reads a compact disc and that is connected to an audio system

Types of CD Drive:

CD-ROM:- CD-ROM stands for (Compact Disc Read Only Memory), and it is

mainly used to mass produce audio CD's and computergames. Computer users

can only read data and music from the discs, but they cannot burn their own

information onto the discs, from their personal computers.

CD-R:- CD-R also known as (Compact Disc Recordable) and WORM (Write Once

Read Many) is a blank disc that users can put into a CD-ROM drive to burn or

make a copy of their personal data, music, videos and information.

CD-RW:- Unlike a CD-R, the CD-RW (Compact Disc Rewritable) can be erased and

returned to its original blank state. New files can then be copied onto the

rewritable disk. CD-RW never became as popular as the CD-R's because they

are not compatible with most disc players to listen to music. They are primarily

used to move data from one computer to another, or to copy files that are only

needed a few times.

Function of CD Drive:-

Data Storage on a CD:- CDs, or compact discs, are composed of fourlayers of material. From bottom to top, the layers are a polycarbonate layer, a

reflective layer, a surface of lacquer and a screen layer to place artwork or

lettering for the CD cover.

Reading the Data:- The main components of a CD/DVD ROM drive are a

small drive motor, a tracking mechanism and a laser/lens assembly, all of

which connect to the motherboard of the computer via a 40-pin ribbon cable.

Interpreting the Data:- The laser lens, after receiving the light from the

laser, reads it as a digital signal.
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Sound Card:-

The sound card is a component inside the computer that provides audio inputand output capabilities. Most sound cards have at least one analog line input and one

stereo line output connection. The connectors are typically 3.5 mm minijacks, which

are the size most headphones use. Some sound cards also support digital audio input

and output, either through a standard TRS (tip-ring-sleeve) connection or via an

optical audio port, such as Toslinkconnector.

Types of Sound Cards

MotherboardSound Chips:- When sound cards were first introduced, they

were expensive add-on cards that cost hundreds of dollars. As computer sound

technology began to come down in price, miniaturization technology enabled

computer hardware manufacturers to condense all of the technology required

to produce sound into a single chip.

Standard Sound Cards:- A standard sound card is an expansion card that

connects to one of the slots inside the computer.

External Sound Adapters:- An external sound adapter is a small box that

contains all of the features of a standard sound card, but connects to the

computer via a USB or FireWire port rather than an internal expansion slot

Function:

The sound card functions as an audio processor for your computer. Analog ordigital signals come into the input of the card and are digitally interpreted as

algorithms which are in turn interpreted as waveforms and produce a sonic

signal in the output of the computer sound card. The sound card is an

installed, running device on your computers system, with programmed

hardware properties and separate device drivers. The sound card controls all

audio on the computer.

Storage Device:

A data storage device is a device for recording (storing) information (data).Recording can be done using virtually any form of energy, spanning from manual
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muscle power in handwriting, to acoustic vibrations in phonographic recording, to

electromagnetic energy modulating magnetic tape and optical discs.

A storage device is a hardware device capable of storing information. There are two

storage devices used in computers; a primary storage device such as computerRAM

and a secondary storage device such as a computerhard disk drive. In the picture tothe right, is an example of a Drobo external secondary storage device.

The two primary storage technologies are magnetic and optical.

The primary types of magnetic storage are:

Disketes (floppy disks)

Hard disks

High-capacity floppy disks

Disk cartridges

Magnetic tape

The primary types of optical storage are:

Compact Disk Read-Only Memory (CD-ROM)

Digital Video Disk Read-Only Memory (DVD-ROM)

o CD-Recordable (CD-R)

CD-Rewritable (CD-RW)

PhotoCD
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PRACTICAL:-2

AIM : Study of Peripheral Devices.

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