Part of the memory that is used to store the actual calculated frame. The frame buffer usually stores 2 frames : one is being calculated by the 3D accelerator while the other one is being send to the monitor, this is called double buffering and delivers smooth animation. For 640x480 resolution with 16 bits color we require 640x480x16x2 = 9830400 bits of memory or about 1.2 Mb of Frame Buffer memory. For 800x600x16b we need 1.8 Mb. For 1024x768x16b we need about 3Mb each value is for 2 frames. Voodoo cards are equipped with 2Mb for the Frame and Z-buffer. It is very clear that no resolutions higher than 800x600 are possible. If you want the Z-buffer you are limited to 640x480. PowerVR uses the Memory of your existing graphics card for Frame Buffering.