Figure 6-18. Read Mode Data Flow - AMD Geode LX 600@0.7W Data Book

Display Controller
6.5.5.4 Read Modes
There are two read modes provided to assist the CPU with
graphics operations in planar modes. Read mode 0 simply
returns the frame buffer data. Read mode 1 allows the CPU
Memory Read Data [31:0]
Read Map Select [1:0]
CPU A[1:0]
Color Compare [3:0]
Color Don't Care [3:0]
ReadMode1
AMD Geode™ LX Processors Data Book
Chain2
Select Read
Map Logic
Chain4
CPU Read Data [7:0]

Figure 6-18. Read Mode Data Flow

to do a single color compare across eight pixels. Figure 6-
18 shows the data flow for read modes. Figure 6-19 on
page 292 shows how the color compare logic in Figure 6-
18 works.
In [31:0]
Out [7:0]
A B
B
33234H
In [31:0]
Color Compare
Logic
Out [7:0]
291