/computer/video memory

To understand computer spec, we need to know what is .
As we already know, a graphic accelerator manages the color of each pixel on our screen. It means that for each pixel the accelerator contains the information about its color.
The place to store this information is called "Video Memory". The color on the screen consists of 3 channels: Red, Green and Blue (RGB). How much video memory do we need? For each pixel it is a standard to have 128 grades of each color of RGB to provide the quality like in a photo (around 2 million colors). It makes the total memory required for each pixel to be 24bit.


Now, we need the memory proportional to the number of pixels on our screen. My screen has a maximal resolution 1280 pixels width and 800 pixels height. So, the minimal amount of video memory required for me should be 1280 x 800 x 24 bit = 24576000 bit = 24576 kilobit (kb) = 3072 kilobyte (kB) (Each byte contains 8 bit) = approximately 3 megabyte.
Modern graphic accelerators have video memory inside starting from 64 megabyte. Since I don't play 3D computer games, for me such amount of memory is a waste.


Video memory is shared with RAM
http://en.wikipedia.org/wiki/Video_memory