بلمومن ح
عدد المساهمات : 971
نقاط : 2540
تاريخ التسجيل : 09/12/2010
العمر : 50
الموقع : belimour
 | موضوع: بحث عن الكمبيوتر باللغة الانجليزية  الخميس ديسمبر 29, 2011 6:30 pm | |
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Parts of a computer If
you use a desktop computer, you might already know that there isn't any
single part called the "computer." A computer is really 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 notebook-sized package. 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. Storage 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. 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. 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. Tip If
you have a recordable CD or DVD drive, periodically back up (copy) your
important files to CDs or DVDs. That way, if your hard disk ever fails,
you won't lose your data. 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. 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. 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. For more information,
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.
You can also use your keyboard to perform many of the same tasks you can perform with a mouse. For more information, . 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. 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. 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. 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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