Chapter 2
AMD-761™ System Controller Programmer’s Interface
51
24081D—February 2002
AMD-761™ System Controller Software/BIOS Design Guide
Preliminary Information
DRAM Timing
Dev0:F0:0x54
Register Description
This register defines the DRAM timing parameters for all banks. BIOS software must set appropriate values in this register
before setting the SDRAM_Init bit (See “Bit Definitions DRAM Mode/Status (Dev0:F0:0x58)” on page 57) or attempting
any DRAM accesses.
Note that this register is not initialized at reset time, and all bits must be initialized by BIOS for proper operation. This
action should be done prior to attempting DRAM access.
31
30
29
28
27
26
25
24
Bit
SBPWaitState AddrTiming_A AddrTiming_B RD_Wait_State Reg_DIMM_En
t
WTR
t
WR
Reset
X
X
X
X
X
X
X
X
R/W
R/W
23
22
21
20
19
18
17
16
Bit
t
RRD
Reserved
Idle_Cyc_Limit
Reset
X
0
0
0
0
X
X
X
R/W
R/W
R
R/W
15
14
13
12
11
10
9
8
Bit
PH_Limit
Reserved
t
RC
t
RP
Reset
X
X
0
0
X
X
X
X
R/W
R/W
R
R/W
7
6
5
4
3
2
1
0
Bit
t
RP
t
RAS
t
CL
t
RCD
Reset
X
X
X
X
X
X
X
X
R/W
R/W