User's Manual

Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0
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12.3.13. BR12—Source Address
Memory Offset Address: 40030h
Default: None
Attributes: RO; DWord accessible
31 26 25 0
Reserved. Must
be Zero
Source Address Bits [25:0]
Bit Descriptions
31:26 Reserved. Must be Zero. The maximum GC Graphics address is 64 MBs.
25:0 Source Address Bits [25:0]. These 26 bits are used to specify the starting pixel address of the color
source dataThe lower 3 bits are used to indicate the position of the first valid byte within the first
Quadword of the source data.
NOTES: This is a working register. If BR12 is read while the BLT Engine is busy, the contents are unpredictable.
The value contained in this register while the BLT Engine is busy has no relationship to the programmed
value that can be read when the BLT Engine is idle.