
Chapter 7
Recommended BIOS Settings
237
24081D—February 2002
AMD-761™ System Controller Software/BIOS Design Guide
Preliminary Information
Registers
-----
Bits
Description
Initialized/
Required
Value
Actual
Value
Key
fcn( )
Notes
0x0x1x40h
DDR PDL Calibration Control
31:8
Reserved
0000_000h
r
7
SW_Recal
Set after setting SW_Cal_Dly
0b
B
Write 1=>Calibration
0=Calibration Complete
1=Calibration Not Complete
6
Use_Act_Dly
Use Actual Delay
0b
B
0=Disable,
1=Enable SW_Recal and
Auto_Cal_En Must = 0
When Use_Act_Dly = 1
5
Auto_Cal_En
Auto Calibration Mode
1b
B
0=Disable
1=Enable
Refer to
AMD-761™ System
Controller Revision Guide
,
order# 23613, for special
instructions for Revision B2
silicon.
4
Act_Dly_Inh
Actual Delay Update Inhibit
0b
B
0=Disable
1=Enable
Refer to
AMD-761™ System
Controller Revision Guide
,
order# 23613, for special
instructions for Revision B2
silicon.
3:2
Reserved
00b
r
1:0
Auto_Cal_Period
Auto-Calibration Period
01b
B
00=10000 System Clocks
01=1000000 System Clocks
10=10000000 System Clocks
11=Reserved
0x0x1x44h
DDR PDL Configuration Register 0
31:24
Clk_Dly
yyh
c
Half Period of the System Clock
23:16
SW_Cal_Dly
xxh
B
FSB
Delay for DQS:
100 MHz = 69h
133 MHz = 6Bh
15:8
Cal_Dly
yyh
c
SW_Cal_Dly in # of Buffers
7:0
Act_Dly
xxh
c
From SW_Recal or Direct Write
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