

  Graphics: Tile Accelerator
  --------------------------

  The Tile Accelerator (TA) accepts rendering primitives from the main CPU,
and performs some preprocessing which the 3D rendering unit needs: the
primitives are stored in graphics memory, and the primitives are added
to their respective tiles.
  It is not necessary to use the TA to build the Tile Arrays; the CPU can
write the Tile Array structure and the primitives to graphics memory
itself, and then tell the 3D rendering unit to render the scene, but using
the TA is pretty much guaranteed to be faster.
(In old PowerVR hardware, there was no TA... the graphics card's driver
 built the Tile Arrays using the CPU instead.)


  Tile Accelerator - overview
  ---------------------------

