Definition: display adapter

A plug-in card in a desktop computer that performs graphics processing. The display adapter determines the maximum resolution, refresh rate and number of colors that can be displayed, which the monitor must also support.

Also called a "graphics card" and "video card," modern display adapters are graphics processing units (GPUs) that use the PCI Express bus. Earlier interfaces were PCI and AGP. These GPU display adapters are all about making video games more realistic. Although all PCs come with display circuits built onto the motherboard, they are bypassed if a GPU card is plugged in. See chipset and graphics card.

Graphics Pipeline
Rendering the video frames is done in several stages, and the final stage turns the image data into pixels. See graphics pipeline.

Digital and Analog Signals
On laptops, the display circuitry has been digital from end to end. However, on desktop computers, the output to the screen has been both digital and analog. Modern graphics cards output digital DisplayPort and HDMI signals. Earlier adapters (CGA, EGA, PGA, DVI) were also digital, which old TV-tube-based monitors (CRTs) converted to analog. Starting with VGA in 1987, adapters sent analog signals to the monitor, and today's monitors may include a VGA input to accommodate older computers. 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.)

More Down to Earth

Although a basic level of graphics circuitry is built into all motherboards, plugging in an external adapter is still required for gaming. (Image courtesy of NVIDIA Corporation.)