Output Devices
Monitors
The
monitor is the primary output device of a computer system.
It is a display device that forms an image by converting electrical signals from
the computer into points (called picture-elements or pixels) of
colored light on the screen. The quality of a monitor is determined by two
factors:
- Number of Picture Elements (pixels)
- Number of colors that can be displayed
Three resolution standards for computer
displays are:
- Video Graphics Array (VGA)
16 colors at 640 x 480 pixels resolution.
- Super VGA
256 colors at 800 x 600 or 1024 x 768 pixels
resolution.
- Extended Graphic Array (XGA)
65,536 colors at 1024 x 768 pixels resolution.
Two types of monitors exists:
- Cathode-Ray Tubes (CRT) these devices are cost
effective high resolution devices. They are however larger in size
that the Flat-Panel monitors.
- Flat-Panel Monitors these monitors where first developed
for portable computers that uses Liquid Crystal Display (LCD)
monitors. The main advantage of these monitors is the size. The
display however is lower in quality and the price is higher than the CRT
monitors.
Two types of Flat-Panel Monitors exists:
- Passive-matrix or dual-scan monitors
create images by scanning the entire screen.
- Active-matrix monitors create sharper images by
directly activating each pixel on the screen. These monitors
however require more power and more expensive.
Printers
Three
popular types are:
- Ink Jet
- Laser
- Thermal
Plotters
Plotters
are special-purpose drawing devices that are used mainly to produce
architectural drawings and three-dimensional illustrations.
Four
types of plotters are:
- Pen
- Ink Jet
- Electrostatic
- Direct-Imaging
Voice Synthesis
Voice
synthesis systems make sounds that resemble human speech. This is
accomplished by use of:
- Pre-recorded vocalized sounds or
- Computer generated sounds.
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