Most computer graphics are shown on a monitor, in the form of a CATHODE- RAY TUBE (CRT). Two display methods are typically used: raster-scan CRTs and vector CRTs. In the more common raster-scan CRT, an electron beam sweeps the screen horizontally many times per second, creating an image that consists of a two-dimensional grid of dots. Each of these dots, or pixels (for picture elements), may be manipulated in color and intensity. In a vector oriented approach, the electron beam sweeps back and forth between two or more points on the screen, creating an image composed of lines.
Text
There is two ways to control text on the screen: DOS character oriented approach and pixel oriented approach. In a DOS character oriented approach you create a symbol table in the memory BIOS. When you draw something you tell which cell and character to draw and go to this table and choose the character you need. You cannot do graphics in character mode. In a Pixel oriented approach your characters are usually stored in fonts. The two type of fonts are: True type fonts and printer fonts. True type fonts appear the same on the screen and printer. There are mathematical hints built in that tell the computer how to draw a certain letter and when enlarged add certain features to the letter. Printer fonts- fonts stored on printer.
Monitors vary in their quality of output, or resolution. Resolution refers to the number of addressable points on the screen - the number of points to which light can be directed. These points are called pixels. Each pixel can be assigned a shade PC displays are in either text mode or graphics mode. Monochrome monitors display everything in one color, while color monitors usually mix red green and blue to achieve a spectrum of colors. Several color video display standard have evolved since the introduction of the IBM PC in 1981.
The four most popular monitors are:
CGA: Color Graphic Adapter (low resolution) 320 by 200 pixels
EGA: Enhanced Graphics Adapter (higher resolution 640 by 350 greater variety in the selection of colors from 4 to 16.
VGA: The Video Graphics Array standard provides a slightly improved resolution to 640 by 489 and uses 256 colors.
Super VGA: provides resolution from 800 by 600 to 1280 by 1024 Monitor display- LCD Liquid Crystal Display, gas plasma. LCD displays use relatively high power.