6.1 Introduction to Multimedia
6.1.2 The video card
A video adapter (also called a display adapter or video board) is an integrated circuit card in a computer that provides digital-to-analog conversion, video RAM, and a video controller so that data can be sent to a computer display. In a few cases, the video adapter is built into the monitor. Today, almost all displays and video adapters adhere to the standard Video Graphics Array (VGA).

VGA is how data is passed between the computer and the display. It is responsible for the frame refresh rates in hertz and the number and width of horizontal lines, which essentially amount to specifying the resolution of the pixels that are created. VGA supports four different resolution settings and two related image refresh rates.

In addition to VGA, most displays adhere to one or more standards set by the Video Electronics Standards Association (VESA). The VESA defines how software can determine the capability of a display. It also identifies resolutions setting beyond those of VGA. These resolutions include 800 by 600, 1024 by 768, 1280 by 1024, and 1600 by 1200 pixels.

What is a display?
A display is a computer output surface and projecting mechanism that shows text and often graphic images, using a Cathode Ray Tube (CRT), Liquid Crystal Display (LCD), light-emitting diode, gas plasma, or other image projection technology. The display is usually considered to include the screen or projection surface and the device that produces the information on the screen. In some computers, the display is packaged in a separate unit called a monitor. In other computers, the display is integrated into a unit with the processor and other parts of the computer. Some sources make the distinction that the monitor includes other signal-handling devices that feed and control the display or projection device. However, there is no distinction when all these parts become integrated into a total unit, as in the case of notebook computers. Displays (and monitors) are sometimes called Video Display Terminals (VDT) or Video Display Units (VDU). The terms display and monitor are often used interchangeably.

Most computer monitors use analog signals to display the image. This requirement and the need to continually refresh the displayed image means that the computer also needs a display or video adapter. The video adapter takes the digital data sent by application programs, stores it in video Random Access Memory (video RAM), and converts it to analog data for the display scanning mechanism using a Digital-to-Analog Converter (DAC).