A graphics display system has a graphics processor system for forming a color
image
on a display, the display being composed of an array of pixels. A memory system
has a first memory for storing at least respective color data and respective Z
data that is render from primitives of the image, and a second memory for storing
respective display data, derived from the rendered color data and Z data, for each
of the pixels. The graphics processor system has a memory interface operatively
connected to the first and second memories. During formation of an image frame,
the memory interface writes to and reads from a Z buffer, and only writes to a
render target color buffer. After the image is rendered, image data is copied from
the first memory to the second memory from which the image is displayed.
