The plug-in card in a desktop computer that creates the electronic signals required by the monitor. Also called a "video card" or "graphics card," modern display adapters use the PCI Express interface, while earlier cards used PCI and AGP. The display adapter determines the maximum resolution, refresh rate and number of colors that can be displayed, which the monitor must also be able to support. On many PC motherboards, the display circuits are built into the chipset, and a separate plug-in card is not required.
The Graphics Pipeline
The display adapter's primary purpose is to continuously convert the graphic patterns (bitmaps) in memory frame buffers into signals for the monitor's screen. However, high-end adapters do a whole lot more. They move the image through a graphics pipeline adding texture and 2D and 3D effects, all functions that used to be done by the computer's CPU. A super fast gaming adapter is a sophisticated parallel processing computer (see graphics accelerator and graphics pipeline).
Analog and Digital Outputs
The first PC display adapters (CGA, EGA, PGA) sent digital signals to the monitor, which converted them into analog for the CRT. Starting in 1987, adapters sent analog VGA signals to the monitor; however, newer adapters output digital DVI or DisplayPort. New flat panel monitors use DVI but also include a VGA socket to accommodate older machines. On laptops, the display circuitry has been digital from end to end. See shared video memory and how to select a PC monitor.
Call It a What?
Take your pick... display adapter, display card, display controller, video adapter, video card, video controller, graphics adapter, graphics card, graphics controller, VGA adapter, VGA card and VGA controller are all terms for the electronic circuits on a plug-in card that create the images for the screen. For popular display resolutions, see resolution.
Visitors used to explore this ceiling-high combination display adapter and sound card at The Computer Museum in Boston. (Image by FAYFOTO/Keith Quenzel; courtesy of The Computer History Museum, www.computerhistory.org.)
Although display circuitry is built into many motherboards, plugging in a high-quality adapter such as this one, based on NVIDIA chips, is still required for the fastest rendering of animation and full-motion video. (Image courtesy of NVIDIA Corporation.)
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