Introduction to Computers
In today’s world wherever we go we are surrounded by various varieties of
computers. They enable us to send or receive data from any part of the world
with a click of a mouse. Today we can write e-mails, play games, watch
television, listen to music, work on our office data, watch video lectures and do
endless things through our computers. Computers today come in many shapes
and sizes like desktop, laptop, palmtods, PDAs etc.
What Is a Computer
A computer is a device that accepts information (in the form of digitalized data)
and manipulates it for some result based on a program or sequence of
instructions on how the data is to be processed. A programmer is a person who
inputs the data into the computer in order to get a desired final result.
Basic Applications of a Computer
Computers have become an important part of our lives. You can use computer to
get information about the reservation of tickets (railways, airplanes and cinema
halls), books in a library, medical history of a person, a place in a map, or the
dictionary meaning of a word. The information may be presented to you in the
form of text, images, video clips, etc.
Education Computers are extensively used, as a tool and as an aid,
for imparting education. Educators use computers to prepare notes
and presentations of their lectures. Computers are used to develop
computer-based training packages, to provide distance education
using the e-learning software, and to conduct online examinations.
Researchers use computers to get easy access to conference and
journal details and to get global access to the research material.
Entertainment Computers have had a major impact on the
entertainment industry. The user can download and view movies,
play games, chat, book tickets for cinema halls, use multimedia for
making movies, incorporate visual and sound effects using
computers, etc. The users can also listen to music, download and
share music, create music using computers, etc.
Sports A computer can be used to watch a game, view the scores,
improve the game, play games (like chess, etc.) and create games.
They are also used for the purposes of training players.
Advertising Computer is a powerful advertising media.
Advertisement can be displayed on different websites, electronicmails
can be sent and reviews of a product by different customers can
be posted. Computers are also used to create an advertisement using
the visual and the sound effects. For the advertisers, computer is a
medium via which the advertisements can be viewed globally. Web
advertising has become a significant factor in the marketing plans of
almost all companies. In fact, the business model of Google is mainly
dependent on web advertising for generating revenues.
Medicine Medical researchers and practitioners use computers to
access information about the advances in medical research or to take
opinion of doctors globally. The medical history of patients is stored
in the computers. Computers are also an integral part of various kinds
of sophisticated medical equipments like ultrasound machine, CAT
scan machine, MRI scan machine, etc. Computers also provide
assistance to the medical surgeons during critical surgery operations
like laparoscopic operations, etc.
Science and Engineering Scientists and engineers use computers for
performing complex scientific calculations, for designing and making
drawings (CAD/CAM applications) and also for simulating and
testing the designs. Computers are used for storing the complex data,
performing complex calculations and for visualizing 3-dimensional
objects. Complex scientific applications like the launch of the
rockets, space exploration, etc., are not possible without the
computers.
Government The government uses computers to manage its own
operations and also for e-governance. The websites of the different
government departments provide information to the users. Computers
are used for the filing of income tax return, paying taxes, online
submission of water and electricity bills, for the access of land record
details, etc. The police department uses computers to search for
criminals using fingerprint matching, etc.
Home Computers have now become an integral part of home
equipment. At home, people use computers to play games, to
maintain the home accounts, for communicating with friends and
relatives via Internet, for paying bills, for education and learning, etc.
Microprocessors are embedded in house hold utilities like, washing
machines, TVs, food processors, home theatres, security devices, etc.
Components of a Computer System A computer is a system of many parts
working together. The physical parts, which you can see and touch, are
collectively called hardware. (Software, on the other hand, refers to the
instructions, or programs, that tell the hardware what to do.) The illustration
below shows the most common hardware in a desktop computer system. Your
system may look a little different, but it probably has most of these parts. A
laptop computer has similar parts but combines them into a single notebooksized
package.
Desktop computer system Let's take a look at each of these parts.
System unit The system unit is the core of a computer system. Usually it's a
rectangular box placed on or underneath your desk. Inside this box are many
electronic components that process information. The most important of these
components is the central processing unit (CPU), or microprocessor, which
acts as the "brain" of your computer. Another component is random access
memory (RAM), which temporarily stores information that the CPU uses while
the computer is on. The information stored in RAM is erased when the computer
is turned off.
Almost every other part of your computer connects to the system unit using
cables. The cables plug into specific ports(openings), typically on the back of
the system unit. Hardware that is not part of the system unit is sometimes called
a peripheral device or device.
System unit Storage and Computer Memory Computer memory is of two
types namely, primary and secondary.
Primary memory :- Alternatively referred to as internal memory, main
memory, and primary memory, primary storage is a storage location that
holds memory for short periods of times while the computer running. For
example, computer RAM and cache are both examples of a primary storage
device. This storage is the fastest memory in your computer and is used to store
data while it's being used. For example, when you open a program data is moved
from the secondary storage into the primary storage.
Secondary Memory :- Secondary memory refers to storage devices, such as hard
drives and solid state drives. It may also refer to removable storage media, such
as USB flash drives,CDs, and DVDs.
Unlike primary memory, secondary memory is not accessed directly by
the CPU. Instead, data accessed from secondary memory is first loaded
into RAM and is then sent to the processor. The RAM plays an important
intermediate role, since it provides much faster data access speeds than
secondary memory. By loading software programs and files into primary
memory, computers can process data much more quickly.
While secondary memory is much slower than primary memory, it typically
offers far greater storage capacity. For example, a computer may have a
one terabyte hard drive, but only 16gigabytes of RAM. That means the computer
has roughly 64 times more secondary memory than primary memory.
Additionally, secondary memory is non-volatile, meaning it retains its data with
or without electrical power. RAM, on the other hand, is erased when a computer
is shut down or restarted. Therefore, secondary memory is used to store
"permanent data," such as the operating system, applications, and user files.
Storage Devices
Your computer has one or more disk drives—devices that store information on a
metal or plastic disk. The disk preserves the information even when your
computer is turned off.
Hard disk drive Your computer's hard disk drive stores information on a hard
disk, a rigid platter or stack of platters with a magnetic surface. Because hard
disks can hold massive amounts of information, they usually serve as your
computer's primary means of storage, holding almost all of your programs and
files. The hard disk drive is normally located inside the system unit.
Hard disk drive CD and DVD drives
Nearly all computers today come equipped with a CD or DVD drive, usually
located on the front of the system unit. CD drives use lasers to read (retrieve)
data from a CD, and many CD drives can also write (record) data onto CDs. If
you have a recordable disk drive, you can store copies of your files on blank
CDs. You can also use a CD drive to play music CDs on your computer.
CD
DVD drives can do everything that CD drives can, plus read DVDs. If you have
a DVD drive, you can watch movies on your computer. Many DVD drives can
record data onto blank DVDs.
Floppy disk drive
Floppy disk drives store information on floppy disks, also
called floppies or diskettes. Compared to CDs and DVDs, floppy disks can store
only a small amount of data. They also retrieve information more slowly and are
more prone to damage. For these reasons, floppy disk drives are less popular
than they used to be, although some computers still include them.
Floppy disk
Why are floppy disks "floppy"? Even though the outside is made of hard plastic,
that's just the sleeve. The disk inside is made of a thin, flexible vinyl material.
Mouse
A mouse is a small device used to point to and select items on your computer
screen. Although mice come in many shapes, the typical mouse does look a bit
like an actual mouse. It's small, oblong, and connected to the system unit by a
long wire that resembles a tail. Some newer mice are wireless.
Mouse
A mouse usually has two buttons: a primary button (usually the left button) and a
secondary button. Many mice also have a wheel between the two buttons, which
allows you to scroll smoothly through screens of information.
When you move the mouse with your hand, a pointer on your screen moves in
the same direction. (The pointer's appearance might change depending on where
it's positioned on your screen.) When you want to select an item, you point to the
item and then click (press and release) the primary button. Pointing and clicking
with your mouse is the main way to interact with your computer.
Keyboard
A keyboard is used mainly for typing text into your computer. Like the keyboard
on a typewriter, it has keys for letters and numbers, but it also has special keys:
- The function keys, found on the top row, perform different functions
depending on where they are used.
- The numeric keypad, located on the right side of most keyboards,
allows you to enter numbers quickly.
- The navigation keys, such as the arrow keys, allow you to move your position within a document or webpage.
Keyboard You can also use your
keyboard to perform many of the same tasks you can perform with a mouse.
Monitor
A monitor displays information in visual form, using text and graphics. The
portion of the monitor that displays the information is called the screen. Like a
television screen, a computer screen can show still or moving pictures.
There are two basic types of monitors: CRT (cathode ray tube) monitors
and LCD (liquid crystal display) monitors. Both types produce sharp images, but
LCD monitors have the advantage of being much thinner and lighter. CRT
monitors, however, are generally more affordable.
LCD monitor (left); CRT monitor (right)
Printer
A printer transfers data from a computer onto paper. You don't need a printer to
use your computer, but having one allows you to print e-mail, cards, invitations,
announcements, and other materials. Many people also like being able to print
their own photos at home.
The two main types of printers are inkjet printers and laser printers. Inkjet
printers are the most popular printers for the home. They can print in black and
white or in full color and can produce high-quality photographs when used with
special paper. Laser printers are faster and generally better able to handle heavy
use.
Inkjet printer (left); laser printer (right)
Speakers
Speakers are used to play sound. They may be built into the system unit or connected with cables. Speakers allow you to listen to music and hear sound effects from your computer.
Computer
speakers
Modem
To connect your computer to the Internet, you need a modem. A modem is a
device that sends and receives computer information over a telephone line or
high-speed cable. Modems are sometimes built into the system unit, but higher-speed
modems are usually separate components.
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