Understanding Monitors
The monitor is the most common type of output device. It may look like a simple television, but it is not. The monitor enables the human eye to interact with the computer. Without a monitor, the computer's output capabilities would be very limited. Imagine if the only output available were in printed or audible form. The monitor enables the computer to translate computer data into text and graphics and display them.
Several types of computer monitors are available, based on different technology standards. The internals of the devices are essentially the same. They all contain an electron gun that shoots electrically charged particles called electrons toward the back of the monitor screen. The screen is coated with a phosphorous material that glows when an electron runs into it. A beam is made up of these electrons that span across (horizontal) and down (vertical) the screen, forming an image.
| Note | Two ways of measuring a monitor's quality are the refresh rate and dot pitch characteristics. The refresh rate signifies the number of times the beam of electrons shot from the electron gun redraws the screen in one second. The dot pitch measures the distance between two dots of the same color on the monitor. |
refresh rate
A measurement of the number of times that an image is redrawn to the screen per second. Measured in Hertz; a higher number is better.
dot pitch
Measures the distance, in millimeters, between two dots of the same color on the monitor.
pixel
Short for picture element. A pixel is one dot in an image.
bit depth
A value for the number of bits that are used to make up a pixel. The higher the number of bits, the more colors that can be displayed.
Video Display Adapter Standards
Video display adapters (the adapter inside your computer that connects to the monitor) have many standards. Each standard consists of specifications for the maximum supported resolution, colors supported for the maximum resolution, and connector type. Each video display adapter type has a different interface to allow for easier identification.
Resolution on the monitor is determined by the number of pixels. A pixel is the smallest addressable unit on a display screen. The higher the pixel resolution (the more rows and columns of pixels), the more information can be displayed.
Pixels are made up of one or more bits. The more bits you have, the greater the bit depth. Greater bit depth means that more shades and colors can be represented. A monochrome monitor uses one bit per pixel. On a color display, there can be 4 to 24 bits per pixel, which provides from 16 to 16 million colors.
This table defines the standards.
| Video Standard | Resolution (Pixels) | Bit Depth | Supported Colors |
|---|---|---|---|
| Monochrome Display Adapter (MDA) | 80 x 25 | 1 | Monochrome (text only) |
| Hercules Graphics Controller (HGC) | 720 x 350 | 1 | Mono (text and graphics) |
| Color Graphics Adapter (CGA) | 320 x 200 | 2 | 4 |
| 640 x 200 | 1 | 2 | |
| Enhanced Graphics Adapter (EGA) | 640 x 350 | 4 | 16 |
| Video Graphics Adapter (VGA) | 640 x 480 | 4 | 16 |
| Super VGA (SVGA) | 800 x 600 | 24 | 16.7 million |
| 1024 x 768 | 24 | 16.7 million | |
| 1280 x 1024 | 24 | 16.7 million | |
| 1600 x 1200 | 24 | 16.7 million | |
| Extended Graphics Array (XGA) | 800 x 600 | 16 | 65,536 |
| 1024 x 768 | 8 | 256 | |
| IBM 8514/A | 1024 x 768 | 8 | 256 |
passive matrix
A flat-panel LCD display technology that uses horizontal and vertical wires with LCD cells at each intersection to create a video image. Passive matrix is considered inferior to active matrix but is less expensive to produce.
active matrix
Sometimes referred to as Thin Film Transistor (TFT), active matrix LCD displays offer superior clarity and color. This is due mostly to faster refresh rates and more powerful LCD cells.
Taking advantage of the latest video technology is not exclusively a function of upgrading to Windows XP or Windows Server 2003. Software upgrades of the operating system only add support for new technologies. Your video display adapter and monitor-the hardware-must support the selected range of supported resolutions and maximum colors to function properly.
You can upgrade your video hardware to support higher resolutions and more colors. A video display adapter with additional memory will support higher-quality video. Many manufacturers include as much as 8MB of RAM on the video card. If you intend to use advanced animation or video features, you can select video cards or 3D graphic accelerator cards that run faster (for smoother images and motion) and have more RAM. In addition to upgrading your video card, you will also need to select a monitor that will support more colors and higher resolutions.
Liquid Crystal Display
Originally designed for watches, liquid crystal displays (LCDs) quickly grew to be a direct contender with traditional tube-based computer screens. The LCD's thin profile makes it suitable for portable devices from laptops to handheld devices. LCDs are becoming so popular that they are being built for desktop use. Their sleek profile looks good in the trendy technology companies of today, and they save on space.
LCD technology is available in two types: passive matrix and active matrix. The screen of passive matrix displays looks faded because the liquid crystal cells have fewer electrodes to maintain solid colors of light. The cells begin to fade before they can be recharged. Active matrix displays have transistors located throughout the display. Each transistor keeps the liquid display cell charged, providing a much brighter and sharper image.
DIN
Deutsch Industrie Norma German standards organization.
PS/2
Also known as the mouse port and DIN 6, PS/2 was developed by IBM for connecting a mouse to the computer. PS/2 ports are supported for mice and keyboards alike.
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