
Chapter 7
Recommended BIOS Settings
219
24081D—February 2002
AMD-761™ System Controller Software/BIOS Design Guide
Preliminary Information
0x0x0x54h
SDRAM Timing
100 MHz
133 MHz
SPD
ns
U
R
U
R
31
SPBWaitState
0b
1b
0 @ 100 MHz , 1 @ 133 MHz FSB
30
AddrTiming_A SPD # 21
0b
1b
0b
1b
0 @ Unbuff, 1 @ Reg DIMM
29
AddrTiming_B, SPD # 21
0b
1b
0b
1b
0 @ Unbuff, 1 @ Reg DIMM
28
RD_Wait_State
1b
1b
Must = 1
27
Reg_DIMM_En, SPD # 21
0b
1b
0b
1b
0 @ Unbuff, 1 @ Reg DIMM
26
t
WTR
= Write Data In to Read CMD
1b
1b
0 = 1 Clock, 1 = 2 Clocks
25:24
t
WR
= Write Recovery Time
10b
10b
00b=1 Clock, 01b=Reserved
10b=2 Clocks, 11b=3 Clocks
23
t
RRD
= Act Bnk A to Act Bnk CMD
SPD # 28
0b
0b
3Ch
15
0 = 2 Clocks, 1 = 3 Clocks
22:19
0000b
0000b
18:16
Idle cycle to wait before
precharging the idle bank
001b
001b
000 = 0 cyc, 001 = 8 cyc (safe)
010 = 12 cyc, 011 = 16 cyc
100 = 24 cyc, 101 = 32 cyc
110 = 48 cyc, 111 = Disable
15:14
Page Hit request before a
nonPage hit
10b
10b
00 = 1 cyc, 01 = 4 cyc
10 = 8 cyc, (safe) 11 = 16 cyc
13:12
00b
00b
11:9
t
RC
= Bank Cycle Time
t
RAS
+ t
RP
or SPD# 41(new, not yet
implemented)
100b
110b
to
111b
41h
to
46h
65
to
70
000 = 3 cyc, 001 = 4 cyc
010 = 5 cyc, 011 = 6 cyc
100 = 7 cyc, 101 = 8 cyc (safe)
110 = 9 cyc, 111 = 10 cyc
8:7
t
RP
= Precharge Time
SPD # 27
01b
00b
50h
20
00 = 3 cyc (safe), 01 = 2 cyc
10 = 1 cyc, 11 = 4 cyc
6:4
t
RAS
= Minimum Bank Active
Time
SPD # 30
011b
100b
to
101b
2Dh
to
32h
45
to
50
000 = 2 cyc, 001 = 3 cyc
010 = 4 cyc, 011 = 5 cyc
100 = 6 cyc, 101 = 7 cyc (safe)
110 = 8 cyc, 111 = 9 cyc
3:2
t
CL
= CAS Latency
SPD # 25 (Not Available)
# 23
# 9
----
01b
01b
10b
10b
----
----
01b
--00b--
10b
A0h
75h
A0h
75h
00 = 3 cyc (optional on DIMM,
not
recommended)
01 = 2 cyc, recommended
10 = 2.5 cyc
11 = reserved
(See 00 above.)
1:0
t
RCD
— RAS to CAS Latency
SPD # 29
01b
10b
50h
20
00 = 1 cyc, 01 = 2 cyc
10 = 3 cyc (safe), 11 = 4 cyc