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Definition: display adapter


A plug-in card in a desktop computer that performs graphics processing. Also commonly called a "graphics card" or "video 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 most PCs, these graphics circuits are built into the motherboard's chipset. A separate plug-in card is required only to greatly enhance rendering for video games or other fast-motion graphics applications. See chipset.

The Graphics Pipeline
The modern display adapter performs two operations. First is rendering, which moves the graphics data through a series of stages that creates the image frames and adds texture and shading (see graphics pipeline). In the first PCs, this was done by the CPU. Today's display circuits are sophisticated parallel processing computers all by themselves (see GPU).

The second function continuously converts the rendered graphic patterns (bitmaps) created in the RAM-based frame buffers into signals for the monitor's screen.

Digital and Analog Signals
Modern adapters output digital DisplayPort and HDMI signals. Earlier adapters (CGA, EGA, PGA, DVI) were also digital, and TV-tube-based monitors (CRTs) converted them to analog. Starting with VGA in 1987, adapters sent analog signals to the monitor; however, today's monitors may include VGA and DVI inputs to accommodate older computers. On laptops, the display circuitry has been digital from end to end. See shared video memory, how to select a PC monitor, CGA, EGA, PGA, DVI, VGA, HDMI and DisplayPort.

Call It What?
Take your pick... display adapter, graphics card, display card, video adapter, video card, graphics adapter, graphics controller, VGA adapter and VGA card have all been terms for the plug-in board that creates the screen images. For a detailed list of adapter resolutions, see screen resolution.




The World's Largest
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.)






More Down to Earth
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.)