232
Recommended BIOS Settings
Chapter 7
AMD-761™ System Controller Software/BIOS Design Guide
24081D—February 2002
Preliminary Information
7.1.2
Examples: AGP Compensation Register Settings (0xB4-0xBB)
TYPEDET#
0x0x0x88[25]
Type_Det = 1 indicates that a card in the AGP slot is a 3.3-V
signalling card, which supports 2X AGP maximum. A 3.3-V
signalling card
cannot
run above 2X AGP.
Type_Det = 0 indicates that a card in the AGP slot is a 1.5-V
signalling card, which supports 4X AGP maximum. A 1.5-V
signalling card can run at 1X, 2X, or 4X AGP rates.
Refer to “AGP Interface” on page 205 for details on how the
value of the Type_Det bit and the settings of the AGP
c o m p e n s a t i o n r e g i s t e r a f f e c t t h e s e t t i n g s i n AG P
Compensation Bypass register.
Type_Det = 1 2X AGP Maximum Type_Det =1 == 3.3-V card in AGP slot
0x0x0x..
B4h
B5h
B6h
B7h
B8h
B9h
BAh
BBh
No Option
48h
00h
01h
C5h
0Fh
FFh
0Fh
C5h
Type_Det = 0 4X AGP Maximum, Reduced to 2X AGP with 4X_Override
0x0x0x..
B4h
B5h
B6h
B7h
B8h
B9h
BAh
BBh
Option 1
4Ah
00h
01h
D8h
8Fh
FFh
04h
D8h
4x_Override and Always_Compensate
0x0x0x..
B4h
B5h
B6h
B7h
B8h
B9h
BAh
BBh
Option 2
48h
00h
01h
D8h
8Fh
FFh
84h
D8h
4x_Override and Bypass
Type_Det = 0 4xAGP Maximum, Options of Always Compensate, Bypass and Fast Writes
0x0x0x..
B4h
B5h
B6h
B7h
B8h
B9h
BAh
BBh
Option 1
02h
00h
01h
D8h
8Fh
FFh
04h
D8h
Always_Compensate
0x0x0x..
B4h
B5h
B6h
B7h
B8h
B9h
BAh
BBh
Option 2
82h
00h
01h
D8h
8Fh
FFh
04h
D8h
Always Compensate and Fast Writes
0x0x0x..
B4h
B5h
B6h
B7h
B8h
B9h
BAh
BBh
Option 3
00h
00h
01h
D8h
8Fh
FFh
84h
D8h
Bypass
0x0x0x..
B4h
B5h
B6h
B7h
B8h
B9h
BAh
BBh
Option 4
80h
00h
01h
D8h
8Fh
FFh
84h
D8h
Bypass and Fast Writes