ATI X800 User Guide - Page 20

17 HYPER Z™ HD HYPER Z™ HD includes a number of different technologies aimed at optimizing memory bandwidth efficiency, particularly with respect to Zbuffer operations. To render a 3D image properly, it is necessary to know the distance of every rendered object from the viewpoint. This distance is stored in a special buffer called a Z-Buffer or Depth Buffer, and is used to determine which objects should be drawn in front of other objects. Reading and updating the Z-Buffer typically consumes more memory bandwidth than any other part of the 3D rendering process, making it a major performance bottleneck. HYPER Z™ HD technology reduces the memory bandwidth consumed by the Z-Buffer, thereby increasing performance. MIP Map Multum In Parvum (Latin) means "many in one." It is a method of increasing quality of a texture map by storing multiple resolutions of the same image and dynamically switching between them depending on the size and depth of the object being textured. Offscreen Memory An area of memory used to preload and place images so that they can be quickly drawn on the screen. Offscreen memory refers to all the memory on your ATI accelerator card that is not taken up by the front buffer, which holds the display screen that you see. Pixel, Pel Picture element. Smallest addressable area of the computer screen. Pixels on computer displays are square; pixels on NTSC televisions have a 4:3 aspect ratio. Refresh Rate Also referred to as "vertical refresh rate". The rate at which a monitor or television can redraw the screen from top to bottom. NTSC television systems have a refresh rate of approximately 60 Hz (but only draw one-half of the video frame in one pass); computer displays typically have refresh rates of 75 Hz or more. At a refresh rate of 70 Hz and lower, screen flicker is often noticeable.