How Video Hardware Works

• A monitor contains an electron gun which scans the screen row-by-row many times a second, activating phosphors which glow in color. Each row is called a scan line, and the period when the gun moves from the end of one scan line to the beginning of the next is a blanking interval.
• A video card contains (at minimum) a frame buffer containing color information for a rectangular grid of pixels and a digital-to-analog converter (RAMDAC) that scans through the buffer and generates a signal for the monitor. The resolution of a mode is the dimensions of the grid, and its color depth is the number of simultaneous colors one can display.