Parts of a computer
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.
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. Picture of a 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; 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.
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.
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.
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.
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 the newer LCD (liquid crystal display) monitors. Both types produce sharp
images, but LCD monitors have the advantage of being much thinner and lighter.
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 material. 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 can 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
