Output Devices

Monitors. Monitors, which look like television sets, quickly display and redisplay the computer's output. They are often called CRTs (cathode ray tubes), VDTs (video display terminals), or simply screens.

The image displayed on the screen is composed of many rows of tiny dots, called pixels (short for picture element). The number and size of pixels determine the resolution (sharpness and clarity) of the display. The more pixels, the higher the resolution.

Each type of monitor, such as monochrome or colour graphics, requires a matching type of display adapter in the system unit.

• Desktop Monitors. CRTs, are the desktop monitors that are built in the same as television sets. They can be monochrome or colour:
• Monochrome monitors show one colour, generally white, green, or amber, on a dark background.
• Colour monitors (often called graphics monitors) display text characters and graphic images in colour. They have advanced through various stages: CGA (colour graphics adapter), EGA (enhanced graphics adapter), and VGA (video graphics array).
• Printers. Printers create paper copies, called hardcopies, of information sent from the computer. Four types of printers are in common use:
• Dot matrix printers use a series of dots to form a character. They are fast and inexpensive, but the output quality can be relatively low.
• Daisy-wheel, or letter-quality, printers create print of the same quality as a typewriter. Letter-quality printers are slower but they produce a higher-quality print.

Ink jet printers spray small droplets of ink to create characters. These printers produce a fine-quality print at an extremely high speed; some print in colour.

Laser printers are quickly taking the place of other printers for most uses. Laser printers produce an exceptionally high-quality print at a very high speed.

Post-reading activity