Video RAM (VRAM)

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Video RAM (VRAM)

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Definition

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 graphical user interfaces (GUIs) 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.

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References

1. Wikipedia: https://en.wikipedia.org/wiki/Video_RAM_(dual-ported_DRAM)