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PROJECT

INTRODUCTION TO COMPUTER

SUBMITTED BY

RAO ALI NOOR

ID # 041040-056

B.COM

BATCH 10(B)

SUBMITTED TO

SIR TARIQ

UNIVERSITY OF

MANAGEMENT AND

TECHNOLOGY LAHORE.

COLLEGE OF COMMERCE AND

ACCOUNTANCY.

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MONITORDefinitions ofmonitor:

Display consisting of a device that takes signals from a computer and

displays them on a CRT screen.

Proctor: someone who supervises (an examination). Admonisher: someone who gives a warning so that a mistake can be

avoided.

An ironclad vessel built by Federal forces to do battle with the

Merrimac.

Electronic equipment that is used to check the quality or content of

electronic transmissions.

A piece of electronic equipment that keeps track of the operation of a

system continuously and warns of trouble.

Keep tabs on; keep an eye on; keep under surveillance.

Any of various large tropical carnivorous lizards of Africa and Asiaand Australia; fabled to warn of crocodiles.

A monitor is a synchronization mechanism that encapsulates the

representation of a shared resource and provides operations that are

the only way of manipulating it. In other words, a monitor contains

variables that represent the state of the resource and procedures that

implement operations on the resource; a process or thread can access

the monitor's variables only by calling one of its procedures. Mutual

exclusion among the procedures of a monitor is guaranteed; execution

of different procedure.

TYPES OF MONITORS

CRTsThe most prevalent type of monitor today is the cathode ray tube (CRT).

Despite its rather sci-fi sounding name, a CRT is the same as the picture

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tube inside your TV. They work by firing beams of electrons at phosphor

dots on the inside of a glass tube. The phosphors in a CRT are chemicals that

emit red, green or blue light when hit by electrons. These monitors are

capable of multiple resolutions, give the best look to full-motion video and

provide better control over colour calibration for graphic artists.

On the down side, they hog a lot of room and weigh more than several sacks

of potatoes. You can get more compact CRTs called short-depth or short-

neck monitors which are a couple of inches shallower than regular CRTs.

Unless space is a primary consideration, most people buy a CRT display

because they offer good performance at an affordable price.

LCDs

In the opposing corner are flat panel displays or LCDs (liquid crystaldisplays) commonly used in laptops and fast becoming popular as desktop

monitors. Their major selling points are a slim profile and lightweight. A

CRT can be deeper than it is wide, whereas a LCD with a base is only about

a hand span deep. No heavy lifting required with a LCD; they weigh less

than half the average CRT. LCDs require half the power of CRTs and emit

much less electromagnetic radiation, which can interfere with other

electronic devices.

In the screen of a LCD monitor, each pixel is produced by a tiny cell, which

contains a thin layer of liquid crystals. These rod-shaped molecules bendlight in response to an electric current. It's the same display technology that

resides in your digital watch but more sophisticated.

LCDs tend to be clearer than CRTs, which can suffer from convergence or

focus difficulties. Their improved clarity means that even small LCDs can

display higher resolutions than the corresponding sized CRT. They also

make small text easier to read. Unlike CRTs, LCD monitors have only one

optimal resolution. At lower resolutions, the screen is redrawn as a smaller

area or all the pixels in the image are blown-up to fill the screen. The lattersolution can make images look jagged and blocky so be sure the resolution

of the LCD is the resolution you want to use.

CRT FEATURES

Refresh Rate

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If you've decided to get a new CRT then it should have a sufficiently high

refresh rate. This refers to how often the screen is redrawn per second. With

low refresh rates you can get screen flicker and eyestrain. Aim for a rate of

75 Hz for a monitor up to 17 inches in size and 85 Hz for any larger monitor.

LCDs are basically flicker free so refresh rates aren't important.

Dot Pitch

Another consideration for CRTs is dot pitch. This is the distance in

millimeters between phosphors of the same colour. The smaller the dot

pitch, the sharper the image. Opt for a dot pitch of 0.26 mm or smaller. You

can measure dot pitch both horizontally and vertically, but monitor specs

usually quote horizontal dot pitch. Occasionally, the dot pitch is measureddiagonally. By multiplying diagonal dot pitch by 0.866, you can calculate

horizontal dot pitch.

CRT Monitor LCD Monitor

LCD FEATURES

Viewing Angle

One of the main disadvantages of LCDs when compared to CRTs is their

limited viewing angle. When viewing a LCD straight on it looks fine. But

the screen will appear washed-out if you move your head over to the sideand look at it from an extreme angle. Low-end LCDs can have viewing

angles of only 100 degrees which won't give everyone crowded round your

desk a clear view. For a standard 15 inch LCD try to get a 140 degree

viewing angle. Up that by 20-40 degrees when shopping for an 18 inch

LCD.

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Brightness

The brightness of LCD monitors is another important factor. LCD monitors

have several backlights that provide illumination. Brightness is measured in

units called nits. The majority of LCDs produce 150-200 nits which is finefor most users. The backlights in a LCD are good for 10 to 50 thousand

hours of operation.

Since they're fairly fragile and more likely to break, backlights usually come

with only a one year warranty. This warranty is separate from the one for the

screen so you might want to extend the backlight warranty to match the

duration of your screen warranty.

Positioning

LCDs can provide a range of options for positioning a display. The common

way to view a screen is landscape mode (longer than wide). Some LCDs let

you pivot the screen 90 degrees so you can view it in portrait mode (taller

than wide), which is great, if you're growing tired of scrolling so often. You

should also check out whether the screen can both tilt and swivel. Easy

adjustment is important if you'll be doing presentations. You can even mount

some LCDs on the wall like a picture.

FLAT PANEL VS. CRT MONITORSAs Flat Panels continue to drop in price, consumers have to choose between

space-saving aesthetics or better-priced screen quality.

If space and aesthetics are important to you, then a flat panel is the way to

go. Compared to CRT displays they use very little power, emit less heat and

radiation, take up a smaller amount of space and are easy on the eyes.

If space is not an issue, it's probably better to get a good quality 19" CRT

monitor than an entry-level 15" flat panel. As well, if you use your computera lot for graphics and games, a CRT offers a sharper and more detailed

display.

The best thing you can do is spend some time at an electronics store and put

a flat panel through its paces. Open up Word and start typing, read the text

and view images and video if possible.

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If you're an apple enthusiast, you're in luck. The Apple flat panels are top of

the line and display incredibly clear images, text and video. The price is

steep but the results are worth it.

PRINTERDefinitions ofprinter:

(Computer science) an output device that prints the results of dataprocessing

A machine that prints The word printer is used to describe a company that provides commercial

printing services, involving typesetting, printing and bookbinding. A computer printer is a computer peripheral device that produces a hard

copy (permanent human-readable text and/or graphics, usually on paper)from data stored in a computer connected to it.

A printer outputs data that is seen on the computer screen. Most printersare used through a parallel port, but some newer ones use USBconnections. USB is somewhat faster, but there's not much of a differencefor printers. Networked computers usually print to a printer through thenetwork card. The most crucial printer measurement is its dots per inchrating. Although this can be misleading, a higher number is generallybetter. Printers are best chosen by actually seeing the quality of the printer

output. Generic term applied to data-processing devices that produce full-size

hard copy from computers. Several printers are used. Among impactprinters: serial printers, line printers, chain printers, bar printers, wheelprinters and matrix printers. Non-impact printers, like ink jet printers, arebased on printing principles similar to those employed in cathode raytubes.

TYPES OF PRINTER

The two main types of printer are impact and non-impact.

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Impact Printersuse a print head containing a number of metal pins,which strike an inked ribbon placed between the print head and the paper.

Some print heads have only 9 pins to make the dots to build up a character;

some have 24 pins, which produce a better resolution.

The two main types of Impact printers are,

Serial printers.

Line printers.

Chain printers.

Bar printers.

Daisy Wheel printers.

Dot Matrix printers.

Serial printers

A port, or interface, that can be used for serial communication, in whichonly 1bit is transmitted at a time.

Most serialports onpersonal computers conform to the RS-232C orRS-422

standards. A serial port is a general-purpose interface that can be used for

almost any type ofdevice, including modems, mice, andprinters (although

most printers are connected to aparallel port).

Line printers

A high-speedprinter capable of printing an entire line at one time. A fast

line printer can print as many as 3,000 lines per minute. The disadvantages

of line printers are that they cannot print graphics, the print quality is low,

and they are very noisy.

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Chain printers

An early line printer that used type slugs linked together in a chain as its

printing mechanism. The chain spins horizontally around a set of hammers.

When the desired character is in front of the selected print column, thecorresponding hammer hits the paper into the ribbon and onto the character

in the chain. Chain and train printers gave way to band printers in the early

1980s.

Chain Printer Mechanism

When the required character in the chain has revolved to the selected printcolumn, the hammer pushes the paper into the ribbon and against the type slugof the letter or digit.

Bar printers

A kind of impact printer in which the character slugs are moved on a type

bar.

Daisy Wheel Printers

An earlier printer that used a rotating plastic or metal wheel with type

characters on the ends of spokes. When the required character spins around

to the print hammer, the image is banged into a ribbon and onto paper.

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Dot Matrix printers

Against ink ribbon to print closely spaced dots in the appropriate shape. Dot-

matrix printers are relatively expensive and do not produce high-quality

output. However, they can print to multi-page forms (that is, carbon copies),

something laser and ink-jet printers cannot do.

Dot-matrix printers vary in two important characteristics:

speed: Given in characters per second(cps), the speed can vary

from about 50 to over 500 cps. Most dot-matrix printers offer different

speeds depending on the quality of print desired.

print quality: Determined by the number of pins (the mechanisms

that print the dots), it can vary from 9 to 24. The best dot-matrix

printers (24 pins) can produce near letter-quality type, although you

can still see a difference if you look closely.

In addition to these characteristics, you should also consider the noise factor.

Compared to laserand ink-jet printers, dot-matrix printers are notorious for

making a racket.

Non-impact printers are much quieter than impact printers as theirprinting heads do not strike the paper.

Most non-impact printers produce dot-matrix patterns.

Several different technologies have been used to provide a variety of

printers.

The main types of non-impact printer are:

Thermal Printers.

Laser Printer.

Ink Jet Printers.

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Thermal Printers

A fax machine uses a thermal printer

Characters are formed by heated elements being placed in contact with

special heat sensitive paper forming darkened dots when the elements reacha critical temperature.

Laser Printer

A laser printer

Laser Printers use a laser beam and dry powdered ink to produce a fine dot

matrix pattern. This method of printing can generate about 4 pages of A4

paper per minute.

Ink Jet Printers

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An inkjet printer

Colour cartridge showing inkjetnozzles

Characters are formed as a result of electrically charged or heated ink being

sprayed in fine jets onto the paper. Individual nozzles in the printing head

produce high resolution (up to 400 dots per inch or 400 dpi) dot matrix

characters.

Inkjet printers use colour cartridges, which combine magenta, yellow and

cyan inks to create colour tones. A black cartridge is also used for crisp

monochrome output.

This method of printing can generate up to 200 cps and allows for good

quality, cheap colour printing.

AUDIO OUTPUT

Audio is a necessary part of any target device. In addition to entertainment it

also provides verbal information to the driver as part of the overall strategy

to control the driver distractions.

Two full-bandwidth stereo output channels are recommended. One

audio output channel should be capable of mixing two input streams at

different input levels to provide its audio output stream. Some examples

that make use of this capability are:

Playing music while the driver listens to navigation instructions or

email being read through the Text-to-Speech (TTS) engine.

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Playing one audio source for the front seat passengers and a

completely different source for the rear seat passengers.

Playing background music with a foreground wave file, talk show,

etc.

AUDIO OUTPUT DIVICES

The following main audio out put devices is used in computer system.

Speakers

Headphone

SPEAKERS

Definition ofSpeakers:

Device that lets you have a conversation with others, listen to music,

or hear sounds generated from the computer.

A loudspeaker is a device which converts an electrical signal into

sound.

An electro acoustic device that is connected as a component in a

computer system, its function being to make speech or music audible.

An output device that allows you to hear voice, music, and other

sounds from your computer.

You need speakers to hear the sound generated by a sound card. Youshould buy speakers with a built-in amplifier to strengthen the sound

signal and improve the performance.

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HEADPHONES

Definition ofHeadphones:

Listening device used under varying circumstances to hear signals.

Placed on your head so you can hear an incoming track while mixing,

headphones are an essential part of DJing. Choose a good quality pair

with closed backs for better bass response and their ability to shut out

external noise. Sony makes good headphones.

Something worn over the ears to allow sound to be heard withoutinterference from other sounds in the room and without sending out

interfering sound. Also known as "cans".

Devices that can be worn on the head with small speakers that fit over

the ears (or sometimes into the ears).

COMBINATION OF INPUT OUTPUT

DIVICES

Combination of input output devices means the devices which are used input

as well as out put also. The following are main input output devices are

Fax Machine Telephone

Mobile Phones

SMS

Pager

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FAX MACHINE

Definition ofFax Machine:

A device that allows the user to fax information over a

communication line.

abbreviation of facsimile machine, a device that can send or receive

pictures and text over a telephone line

Fax (short for facsimile or telefacsimile) is a telecommunications

technology used to transfer copies of documents, especially usingaffordable devices operating over the telephone network. Such faxes

became affordable and very popular in the 1980s. They transfer one or

a few printed or handwritten pages per minute in black-and-white

(bitonal) at a resolution of 100x200 or 200x200 dots per inch. The

transfer rate is 14.4 kilobits per second (kbit/s) or higher.

TELEPHONE

Definition ofTelephone:

A device that converts your speech into an analog signal suitable for

transmission over a phone line.

Electronic equipment that converts sound into electrical signals that

can be transmitted over distances and then converts received signalsback into sounds; "I talked to him on the telephone".

Call: get or try to get into communication (with someone) by

telephone; "I tried to call you all night"; "Take two aspirin and call me

in the morning".

Transmitting speech at a distance.

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MOBIL PHONES

Definition ofMobile phones:

A mobile phone is a wireless device which behaves as a normal telephone

whilst being able to move over a wide area (compare cordless phone which

acts as a telephone only within a limited range). Mobile phones allow

connections to be made to the telephone network, normally by directly

dialing the other party's number on an inbuilt keypad. Most current mobile

phones use a combination ofradio wavetransmission and conventional

telephonecircuit switching, thoughpacket switching is already in use for

some parts of the mobile phone network, especially for services such as

Internet access and WAP.

SMS

It is Short Message service; also commonly known as a text message.

Short Message Service: available on digital GSM networks allowing

text messages of up to 160 characters to be sent and received via the

network operator's message center to your mobile phone, or from the

Internet, using a so-called "SMS gateway" website. If the phone is

powered off or out of range, messages are stored in the network and

are delivered at the next opportunity.

Short Message Service. Electronic messages on a wireless network,

such as those used in two-way paging.

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Short Message Service - Short text messages that can be sent to a

mobile phone.

PAGER

Definition ofPager:

A module responsible for providing the data for the pages of a

memory object. See also default pager; vnode pager.

One-way communications device in which the intended receiver is

alerted to receive a message or return a phone call.

An X program that allows the user to see and switch between multipledesktops.

Small portable receivers that are generally inexpensive, reliable, and

have nationwide coverage. Pagers began as one-way devices, but two-

way paging capabilities are available over some networks, notably

packet data and narrowband PCS networks.

Means an instrument, apparatus or appliance which is a non-speech,

one way personal calling system either alert and has the capability of

receiving, storing and displaying numeric or alpha-numeric messages.