Video RAM (dual-ported DRAM)

Video RAM, or VRAM, is a dual-ported variant of dynamic RAM (DRAM), which was once commonly used to store the framebuffer in some graphics adapters.

It was invented by F. Dill, D. Ling and R. Matick at IBM Research in 1980, with a patent issued in 1985 (US Patent 4,541,075). The first commercial use of VRAM was in a high-resolution graphics adapter introduced in 1986 by IBM for the PC/RT system, which set a new standard for graphics displays. Prior to the development of VRAM, dual-ported memory was quite expensive, limiting higher resolution bitmapped graphics to high-end workstations. VRAM improved the overall framebuffer throughput, allowing low cost, high-resolution, high-speed, color graphics. Modern GUI-based operating systems benefitted from this and thus it provided a key ingredient for proliferation of graphic user interfaces throughout the world at that time.

VRAM has two sets of data output pins, and thus two ports that can be used simultaneously. The first port, the DRAM port, is accessed by the host computer in a manner very similar to traditional DRAM. The second port, the video port, is typically read-only and is dedicated to providing a high throughput, serialized data channel for the graphics chipset.

Video card

A video card (also called a video adapter, display card, graphics card, graphics board, display adapter, graphics adapter or frame buffer) is an expansion card which generates a feed of output images to a display (such as a computer monitor). Frequently, these are advertised as discrete or dedicated graphics cards, emphasizing the distinction between these and integrated graphics. Within the industry, video cards are sometimes called graphics add-in-boards, abbreviated as AIBs, with the word "graphics" usually omitted.

History

Standards such as MDA, CGA, HGC, Tandy, PGC, EGA, VGA, MCGA, 8514 or XGA were introduced from 1982 to 1990 and supported by a variety of hardware manufacturers.

Virtually all current video cards are built with either AMD-sourced or Nvidia-sourced graphics chips. Most video cards offer various functions such as accelerated rendering of 3D scenes and 2D graphics, MPEG-2/MPEG-4 decoding, TV output, or the ability to connect multiple monitors (multi-monitor). Video cards also have sound card capabilities to output sound along with the video for connected TVs or monitors with integrated speakers.