290 AMD Geodeā„¢ LX Processors Data Book
Display Controller
33234H

6.5.5.3 Write Modes

There are four write modes supported by the graphics con-

troller (mode 0, 1, 2, and 3). These write modes provide

assistance to the CPU when the frame buffer is in a planar

graphics format. Figure 6-17 shows the data flow logic that

supports these modes.

Figure 6-17. Write Mode Data Flow
CPU Data [7:0]
Rotator
Data Rotate [2:0]
Set/Reset [3:0] 3210
3210
B
WriteMode2
BBBB
Enable Set/Reset [3:0]
3210
Bit Mask [7:0]
-A/+A*B
Write Mode 3
A
Read Data Latch [31:0]
ALU
Function [1:0]
31:24 23:16 15:8 7:0
Map 3
Write Data
Map 2
Write Data
Map 1
Write Data
Map 0
Write Data
F
ABABABAB
AB AB AB AB
AB
DMSDMSDMSDMS
N
D
Memory Maps
88 88
8888
8
8888
8