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AMD Geode™ LX Processors Data Book 17
Architecture Overview
33234H
2.5 Graphics Processor
The Graphics Processor is based on the graphics proces-
sor used in the AMD Geode GX processor with several fea-
tures added to enhance performance and functionality. Like
its predecessor, the AMD Geode LX processor’s Graphics
Processor is a BitBLT/vector engine that supports pattern
generation, source expansion, pattern/source transpar-
ency, 256 ternary raster operations, alpha blenders to sup-
port alpha-BLTs, incorporated BLT FIFOs, a GeodeLink
interface and the ability to throttle BLTs according to video
timing. Features added to the Graphics Processor include:
• Command buffer interface
• Hardware accelerated rotation BLTs
• Color depth conversion
• Paletized color
• Full 8x8 color pattern buffer
• Channel 3 - third DMA channel
• Monochrome inversion
Table 2-1 presents a comparison between the Graphics
Processor features of the AMD Geode GX and LX proces-
sors.
Table 2-1. Graphics Processor Feature Comparison
Feature AMD Geode™ GX Processor AMD Geode™ LX Processor
Color Depth 8, 16, 32 bpp 8, 16, 32 bpp (A) RGB 4 and 8-bit indexed
ROPs 256 (src, dest, pattern) 256 (2-src, dest and pattern)
BLT Buffers FIFOs in Graphics Processor FIFOs in Graphics Processor
BLT Splitting Managed by hardware Managed by hardware
Video Synchronized BLT/Vector Throttle by VBLANK Throttle by VBLANK
Bresenham Lines Yes Yes
Patterned (stippled) Lines No Yes
Screen to Screen BLT Yes Yes
Screen to Screen BLT with
mono expansion
Ye s Ye s
Memory to Screen BLT Yes (through CPU writes) Yes (throttled rep movs writes)
Accelerated Text No No
Pattern Size (Mono) 8x8 pixels 8x8 pixels
Pattern Size (Color) 8x1 (32 pixels) 8x8 pixels
8x2 (16 pixels)
8x4 (8 pixels)
Monochrome Pattern Yes Yes (with inversion)
Dithered Pattern (4 color) No No
Color Pattern 8, 16, 32 bpp 8, 16, 32 bpp
Transparent Pattern Monochrome Monochrome
Solid Fill Yes Yes
Pattern Fill Yes Yes
Transparent Source Monochrome Monochrome
Color Key Source Transparency Y with mask Y with mask
Variable Source Stride Yes Yes
Variable Destination Stride Yes Yes
Destination Write Bursting Yes Yes
Selectable BLT Direction Vertical and Horizontal Vertical and Horizontal
Alpha BLT Yes (constant α or α/pix) Yes (constant α, α/pix, or sep. α channel)
VGA Support Decodes VGA Register Decodes VGA Register
Pipeline Depth 2 ops Unlimited
Accelerated Rotation BLT No 8, 16, 32 bpp
Color Depth Conversion No 5:6:5, 1:5:5:5, 4:4:4:4, 8:8:8:8