Dual-ported video RAM

This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these messages) This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Dual-ported video RAM" – news · newspapers · books · scholar · JSTOR (April 2009) (Learn how and when to remove this message) This article needs to be updated. Please help update this article to reflect recent events or newly available information. (February 2018) (Learn how and when to remove this message)

Dual-ported video RAM (VRAM) is a dual-ported RAM variant of dynamic RAM (DRAM), which was once commonly used to store the Framebuffer in Graphics card,

Dual-ported RAM allows the CPU to read and write data to memory as if it were a conventional DRAM chip, while adding a second port that reads out data. This makes it easy to interface with a Video display controller (VDC), which sends a timing signal to the memory and receives data in the correct sequence as it draws the screen. Because the CPU and VDC access the memory simultaneously on different ports, dual-ported RAM does not require the CPU to pause while the VDC uses memory, thereby eliminating the associated Wait states and improving overall system performance.

Dual-ported RAM was common from the mid-1980's into the mid-1990's. After that date, new forms of high-performance memory began to be used that eventually replaced dual-ported designs. As these other forms of memory are also known as video memory, and thus VRAM, it sometimes confused with this older form of memory.