Product specifications

VT8601A Apollo PLE133
Revision 1.82 October 22, 2001 -125 3D Graphics Engine Registers
Technologies, Inc.
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Pixel Engine Registers
The major responsibilities of the Pixel Engine are to perform
per-pixel operations and to control data flow and its sequence.
The Pixel engine interfaces to the Rasterization Engine and the
host to accept data. It also interfaces to the Memory Interface
to access video memory. Inside the Pixel Engine, there are
several blocks: the Span Engine, the Data Path, and the
Texture Engine. Operation of the Data Path and the Texture
Engine are under control of the Span Engine. The Memory
Interface accepts memory access requests from the Pixel
Engine, translates the address into a linear address, and
executes the requests.
The 0 - FFh “Engine” register address space is partitioned
into six sections:
0 - 0Fh Span Engine
10 - 2Fh VGA core
30 - 3Fh Unified Rasterization and Setup Engines
44 - 9Fh Pixel Engine
A0 – AFh Texture Engine
B0 – BFh Command List Control Unit
C0 – FFh Memory Interface
Addresses 40h - FFh are also used for sequential loading
overlapping with other registers in this space. Addresses
10000 - 1FFFFh are used as a data port area.
Data from the Host
The Pixel Engine can accept data from the host through either
the 32-bit data port register at 9Ch or data in the 1xxxh
address space. Software passes only enough DWORDs to
hardware. Software doesn’t pack data to 64-bit
boundaries. It only packs to 32-bit boundaries. For bitblts,
packing is done per-scanline. I.e., for every scanline, the host
will send just enough DWORDs to the engine. For text,
packing is done per-command. I.e., the scanline may be
broken inside a DWORD. For a string of texts, the number of
DWORDs of data passed to the Graphic Engine can be odd
numbers except for the last character. For the last character,
software should pass either an even number of DWORDs (by
padding a garbage DWORD as necessary) or by setting a
drawing environment register after all data is sent.
A
D A
D
AGP
Memor
y
Interface
Rasterization
S
p
an
Data Path Texture Engine