KNOWING OUTPUT DEVICES IN THE COMPUTER

An output device displays computer data in human readable

 form. For example, monitors display information on a screen

 from the CPU.

(i)  Monitor

The following table summarizes the two most common types

 of monitors:

Monitor Name	Acronym	Description
Cathode-Ray Tube	CRT	Vacuum tube used  as display screen,  larger monitor that  resembles standard TV
Liquid Crystal  Display	LCD	Uses rod shaped  molecules called  liquid crystals,  often called “flat  panel”

 

Television screens have been using CRT technology for many years. CRT monitors are reliable and provide a good picture. Unfortunately, they are not very efficient (when it comes to the use of power), and there is a large amount of lead used in the tubes to protect users from potentially harmful exposure to x-rays. Since items that contain lead are not easily disposed of, the disposition of old CRT monitors is creating environmental problems in many states. In addition, because these monitors contain tubes that are made of lead, they are usually very heavy and difficult to move around. LCD monitors, or flat panels, are more energy-efficient and produce less heat than CRT monitors. Since they do not contain the lead tubes that are used in CRT technology, they are more environmentally friendly. They are usually smaller than CRT monitors and they require less desk space. They produce very little glare, and the picture quality is usually very good. LCDs have become very popular and affordable in the last few years.

 

                     LCD Monitor                                          CRT Monitor

(ii)  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.

              Inkjet printer (left);                                            laser printer (right) 

(iii) 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.

(iv) 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.

(v) 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.

(vi) 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.

(a) 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.

(b) 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.

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.

(c) 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 these disks called "floppy" disks? The outside is made of hard plastic, but that's just the sleeve. The disk inside is made of a thin, flexible vinyl material.

PREVIOUS  LESSON                                                                        NEXT LESSON