
Chapter 7
Recommended BIOS Settings
233
24081D—February 2002
AMD-761™ System Controller Software/BIOS Design Guide
Preliminary Information
Registers
-----
Bits
Description
Initialized/
Required
Value
Actual
Value
Key
fcn( )
Notes
0x0x0xC0h
Memory Base Address
Register 0
31:23
CS_Base
Chip-Select Base 0
Bank 0 base address
Starting address of the bank
Map to AD[31:23]
xxh xb
B
Set by memory sizing routines
0000_0000_0b = 0
0000_0001_0b = 16 Mbytes
0000_0010_0b = 32 Mbytes
0000_0011_0b = 48 Mbytes
0000_1000_0b = 128 Mbytes
0001_0000_0b = 256 Mbytes
0010_0000_0b = 512 Mbytes,
etc.
22:16
Reserved
000b 0h
r
15:7
CS_Mask
Chip-Select Mask 0
Bank 0 address mask
Sizes the bank
Map to AD[31:23]
xxh xb
B
Set by memory sizing routines
0000_0000_1b = 16 Mbytes
0000_0001_1b = 32 Mbytes
0000_0011_1b = 64 Mbytes
0000_0111_1b = 128 Mbytes
0000_1111_1b = 256 Mbytes
0001_1111_1b = 512 Mbytes
0011_1111_1b = 1 Gbyte
0111_1111_1b = 1 Gbyte
6:3
Reserved
0h
r
2:1
Addr_Mode
Size of Device = Size of Bank x
(Primary SDRAM Width /8)
xxb
B
SPD
# 31
and
13
01b=SDRAM device
<256 Mbits
10b=SDRAM device
>128 Mbits
00b and 11b are reserved
0
Enable/Disable Bank 1
xb
B
0=Disable CS, 1=Enable CS
0x0x0xC4h
Memory Base Address
Register 1
31:23
Chip-Select Base 1
xxh xb
B
As 0x0x0xC0h above
22:16
Reserved
000b 0h
r
As 0x0x0xC0h above
15:7
Chip-Select Mask 1
xxh xb
B
As 0x0x0xC0h above
6:3
Reserved
0h
r
As 0x0x0xC0h above
2:1
Addr_Mode
xxb
B
As 0x0x0xC0h above
0
Enable/Disable Bank 1
xb
B
As 0x0x0xC0h above
KEY:
B= Mandatory BIOS function
A= AGP setup by BIOS
c = Calculated/set by AMD-761™ internal logic
P= Power management setup by BIOS
o = Setup by OS or OS driver
F = Performance enhancement set by BIOS
r = Hardcoded and reserved
u = PCI operational user interface
E = Elective BIOS function