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.
 MONITOR
Definitions of monitor:

• 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 Asia
and 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
CRTs
The 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
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 crystal
displays) 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 bend
light 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 latter
solution 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
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 measured
diagonally. 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 side
and 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.
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 fine
for 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 MONITORS

As 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 computer
a 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.
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.

PRINTER
Definitions of printer:

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

processing

• 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 printers
are used through a parallel port, but some newer ones use USB
connections. USB is somewhat faster, but there's not much of a difference
for printers. Networked computers usually print to a printer through the
network card. The most crucial printer measurement is its dots per inch
rating. Although this can be misleading, a higher number is generally
better. 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 impact
printers: serial printers, line printers, chain printers, bar printers, wheel
printers and matrix printers. Non-impact printers, like ink jet printers, are
based on printing principles similar to those employed in cathode ray
tubes.

TYPES OF PRINTER
The two main types of printer are impact and non-impact.
Impact Printers use 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 which
only 1 bit is transmitted at a time.
Most serial ports on personal computers conform to the RS-232C or RS-422
standards. A serial port is a general-purpose interface that can be used for
almost any type of device, including modems, mice, and printers (although
most printers are connected to a parallel port).

Line printers
A high-speed printer 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.
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, the
corresponding 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 print
column, the hammer pushes the paper into the ribbon and against the type slug
of 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.
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 laser and ink-jet printers, dot-matrix printers are notorious for
making a racket.

Non-impact printers are much quieter than impact printers as their

printing 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.
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 reach
a 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

 Colour cartridge showing inkjet
nozzles

An inkjet printer

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.
 • 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 of Speakers:
• 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. You
should buy speakers with a built-in amplifier to strengthen the sound
signal and improve the performance.
HEADPHONES
Definition of Headphones:

• 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 without

interference 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
FAX MACHINE

Definition of Fax 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 using
affordable 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 of Telephone:

• 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 signals
back 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.
MOBIL PHONES

Definition of Mobile 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 of radio wave transmission and conventional
telephone circuit switching, though packet 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.
 • Short Message Service - Short text messages that can be sent to a
mobile phone.

PAGER
Definition of Pager:

• 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 multiple
“desktops”.

• 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.