RAMDAC

A RAMDAC (random-access memory digital-to-analog converter) is a combination of three fast digital-to-analog converters (DACs) with a small static random-access memory (SRAM) used in computer graphics display controllers or video cards to store the color palette and to generate the analog signals (usually a voltage amplitude) to drive a color monitor. The logical color number from the display memory is fed into the address inputs of the SRAM to select a palette entry to appear on the data output of the SRAM. This entry is composed of three separate values corresponding to the three components (red, green, and blue) of the desired physical color. Each component value is fed to a separate DAC, whose analog output goes to the monitor, and ultimately to one of its three electron guns (or equivalent in non-CRT displays). RAMDACs became obsolete as DVI, HDMI, DisplayPort and other digital interface technology became mainstream, which transfer video data digitally (via transition-minimized differential signaling or low-voltage differential signaling) and defer digital-to-analog conversion until the monitor's pixels are actuated.