Figure 1-13.Monitor controls, switches, and indicators

Quite often, the term monitor is used interchangeably with such names as screen, display, display device, and cathode-ray tube (crt). Monitors can display information in either monochrome or color, depending on their design. Monochrome displays produce output images using a single foreground color, such as black, and a single background color, such as white. This provides you with black text on a white background. Using a technique known as reverse video (that is, reversing the color of the pixels or dots on the screen), it is possible to have white text on a black background. Monochrome displays also come in amber (a yellowish brown) and green. Amber and green are considered more pleasing and less stressful to the eyes than black and white. Most color displays are of the red-green-blue (RGB) type. Depending upon the sophistication of the display device and the amount of RAM available with the microcomputer, you may be able to display from 8 to 16,000,000 colors. Now, let’s take a closer look and discuss some of the more common features you are likely to find on moni- tors. These include brightness, contrast, and sizing. We will also discuss the various types of video display and graphics boards/cards that are used to support them. You use the brightness control to vary the brightness of displayed data. When adjusting this control, you turn the dial until the intensity is at the brightness level desired. Use the contrast control to vary the difference between the nonintensified colors and the intensified colors. Monitors with a sizing feature allow you to increase or decrease the physical size (the height and width) of the displayed information on your screen. Some models use control knobs. Others use two-position switches. Depending on the type monitor you have, these control knobs or switches could be located just about anywhere; on the back, on the sides, or tucked away underneath the monitor to keep them from being accidentally hit, as shown in figure 1-13. Located on the front of most monitors, generally below the screen, you will find some type of power on/off switch. It will probably have a green light- emitting diode (LED) indicator light. When this light is lit, the monitor is on and power is supplied. At this point, it would be helpful for you to have a basic understanding of display technology, along with the various types of display/graphics cards used to support display devices. Having a good working knowledge in this area will put you in a better position to assist the end users in answering any technical questions they may have, as well as aid you in troubleshooting and diagnostics testing. A key characteristic of any display device is its resolution, which determines the sharpness and clarity of the screen image. If you look closely at your display, you’ll notice that images are formed by lighting up tiny dots on the screen. Resolution is measured by the number of these dots or pixels (short for picture elements) per square inch of screen. Whether you are working with text or graphic images, the more pixels used to form characters/images and the more pixels that can be packed per square inch of screen, the higher the resolution and the sharper the character/image. For example, a display resolution of 1280 by 1024 means that the screen consists of 1280 vertical columns by 1024 horizontal rows of dots, or if you prefer 1280 × 1024 = 1,310,720 pixels. The distance between the dots is called dot pitch. Smaller pitch values indicate sharper images. The original IBM PC color monitor had a dot pitch of 0.43mm. The state-of-the-art displays marketed today have a dot pitch of 0.28mm or less. Most display devices are capable of providing you with both text and graphics (pictures). Text output consists of letters, numbers, and special characters only. Text characters are created on the screen in the form of a Figure 1-13.—Monitor controls, switches, and indicators. 1-15