1. Video RAM Presented by GHOLAMREZA KAKAMANSHADI
PANJAB UNIVERSITY, CHD, INDIA
Nov. 2014

2. Video RAM
Video adapters rely on their own onboard memory that they use to store video images while processing them.
The AGP specification supports the use of system memory for 3D textures, this feature is infrequently supported, now that video cards routinely ship with 32MB, 64MB, or more of onboard memory.

3. Many low-cost systems with onboard video use the universal memory architecture (UMA) feature to share the main system memory. In any case, the memory on the video card or borrowed from the system performs the same tasks.
The amount of memory on the adapter or used by integrated video determines the maximum screen resolution and color depth the device can support. You often can select how much memory you want on a particular video adapter; for example, 32MB, 64MB, and 128MB are common choices today.

4. Adding more memory is not guaranteed to speed up your video adapter, it can increase the speed if it enables a wider bus (from 64 bits wide to 128 bits wide) or provides non display memory as a cache for commonly displayed objects.
It also enables the card to generate more colors and higher resolutions and, for AGP cards allows 3D textures to be stored and processed on the card, rather than in slower main memory.

5. Memory Types Used in Video Display Adapters

6. VRAM and WRAM are dual-ported memory types that can read from one port and write data through the other port.
This improves performance by reducing wait times for accessing the video RAM compared to FPM DRAM and EDO DRAM.

7. SGRAM, SDRAM, DDR, and DDR-II SDRAM which are derived from popular motherboard memory technologies have replaced VRAM, WRAM, and MDRAM as high-speed video RAM solutions.
Their high speeds and low production costs have enabled even inexpensive video cards to have 16MB or more of high-speed RAM onboard.

8. Video RAM Speed
Video cards with the same type of 3D graphics processor chip (GPU) onboard might use different speeds of memory.
For example, two cards that use the NVIDIA GeForce FX 5200 the Prolink PixelView and the Chaintech A-FX20 use different memory speeds. The Prolink card uses 4ns memory, but the Chaintech card uses 5ns memory.
Sometimes, video card makers also match different memory speeds with different versions of the same basic GPU, as with ATI’s Radeon 9800 XT and 9800 Pro. The 9800XT has a core clock speed of 412MHz, versus the 9800 Pro’s 380MHz clock speed.

9. RAM Calculations
The amount of memory a video adapter needs to display a particular resolution and color depth is based on a mathematical equation.
A location must be present in the adapter’s memory array to display every pixel on the screen, and the resolution determines the number of total pixels.
For example, a screen resolution of 1024×768 requires a total of 786,432 pixels.

10. If you want to display that resolution with only two colors, you would need only 1 bit of memory space to represent each pixel.
If the bit has a value of 0, the dot is black, and if its value is 1, the dot is white.
If you use 24 bits of memory space to control each pixel, you can display more than 16.7 million colors because 16,777,216 combinations are possible with a 4-digit binary number ( 2 24 =16,777,216).

11. 1024×768 = 786432 pixels×24 bits per pixel
If you multiply the number of pixels necessary for the screen resolution by the number of bits required to represent each pixel, you have the amount of memory the adapter needs to display that resolution.
1024×768 = pixels×24 bits per pixel
= 18,874,368 bits
= 2,359,296 bytes
= 2.25MB
At 1024×768 resolution requires exactly 2.25MB of RAM on the video adapter.
Amounts of only
256KB, 512KB, 1MB, 2MB, or 4MB

12. Video Display Adapter Minimum Memory Requirements for 2D Operations
2D graphics operations, such as photo editing, presentation graphics, desktop publishing, and Web page design.

13. video adapter with 4MB can display 65,536 colors in 1600×1200 resolution mode
But to display 16.8 million colors, you would need to upgrade to 8MB
you would need to replace your current video card with a new one with more memory

14. 3D video cards require more memory for a given resolution and color depth because the video memory must be used for three buffers: the front buffer, back buffer, and Z-buffer.

15. Note
If your system uses integrated graphics and you have less than 256MB of RAM, you might be able to increase your available graphics memory by upgrading system memory (system memory is used by the integrated chipset).
Most recent Intel chipsets with integrated graphics automatically detect additional system memory and adjust the size of graphics memory automatically.

16. Note
The earliest AGP cards had relatively small amounts of onboard RAM, but recent and all current implementations of card-based AGP use large amounts of on-card memory and use a memory aperture to transfer data more quickly to and from the video card’s own memory.

17. The end