Product specifications

ProSavageDDR P4M266 – VT8751 P4 DDR SMA North Bridge
Revision 1.1, July 19, 2002 -46- Device 0 Register Descriptions
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Technologies, Inc.
AGTL+ I/O Control
Device 0 Offset D8 – Host Address (2x) Pullup Drive....RW
7 Reserved ........................................ always reads 0
6-4 Strobe Pullup Drive (HAS#) ................... default = 0
3 Reserved ........................................ always reads 0
2-0 Address Pullup Drive (HA,HREQ#) ...... default = 0
Device 0 Offset D9 – Host Address (2x) Pulldown DriveRW
7 Reserved ........................................ always reads 0
6-4 Strobe Pulldown Drive (HAS#) .............. default = 0
3 Reserved ........................................ always reads 0
2-0 Address Pulldown Drive (HA,HREQ#) . default = 0
Device 0 Offset DA – Host Data (4x) Pullup Drive.........RW
7 Reserved ........................................ always reads 0
6-4 Strobe Pullup Drive (HDS,HDS#) .......... default = 0
3 Reserved ........................................ always reads 0
2-0 Address Pullup Drive (HD,HDBI#)........ default = 0
Device 0 Offset DB – Host Data (4x) Pulldown Drive ....RW
7 Reserved ........................................ always reads 0
6-4 Strobe Pulldown Drive (HDS,HDS#) ..... default = 0
3 Reserved ........................................ always reads 0
2-0 Address Pulldown Drive (HD,HDBI#)... default = 0
Note: Refer to the VT8751 BIOS Porting Guide for
recommended settings for these bits for typical system
configurations.
Device 0 Offset DC – Output Delay / Stagger Control...RW
7-6 Data / Strobe Relative Delay
00 Data delay = strobe delay + 150 psec.....default
01 Data delay = strobe delay
10 Data delay = strobe delay – 150 psec
11 Data delay = strobe delay – 300 psec
5 HD[63:48, 31:16], HDBI[3,1]# Output Stagger
0 No delay.................................................default
1 1 nsec delay
4 HA[31:17] Output Stagger
0 No delay.................................................default
1 1 nsec delay
3-2 HDS / HDS# Output Extra Delay
00 No delay.................................................default
01 150 psec delay
10 300 psec delay
11 450 psec delay
1-0 HAS # Output Extra Delay
00 No delay.................................................default
01 150 psec delay
10 300 psec delay
11 450 psec delay
Device 0 Offset DD – AGTL+ I/O Control (00h) ........... RW
7 AGTL+ 4x Input Increase Delay to Filter Noise
0 Disable................................................... default
1 Enable
6 AGTL+ 2x Input Increase Delay to Filter Noise
0 Disable................................................... default
1 Enable
5 AGTL+ Slew Rate Control
0 Disable................................................... default
1 Enable
4 Reserved ........................................always reads 0
3 Input Pullup
0 Disable................................................... default
1 Enable
2 AGTL+ Strobe Internal Termination Pullups
0 Disable................................................... default
1 Enable
1 AGTL+ Data Internal Termination Pullups
0 Disable................................................... default
1 Enable
0 AGTL+ Dynamic Compensation
0 Disable................................................... default
1 Enable
Device 0 Offset DE – AGTL+ Comp Status (00h) ......... RW
7 Select AutoCompensation Drive
0 Disable................................................... default
1 Enable (RxD8-DB set automatically on-chip
based on auto compensation results)
6-4 AGTL+ Compensation Result ................ default = 0
3 AGTL+ POS Function
0 Inputs always powered .......................... default
1 Inputs powered down when not in input mode
2 DBI Double Check
0 Disable................................................... default
1 Enable (bit-1 must also be 1)
1 DBI (Dynamic Bus Inversion) Function
0 Enable.................................................... default
1 Disable (DBI always high)
0 Reserved ........................................always reads 0
Device 0 Offset DF – AGTL+ Auto Comp Offset (00h). RW
7-4 AGTL+ Drive Offset to Comp Result for 2x Pad
.............................................. default = 0
3-0 AGTL+ Drive Offset to Comp Result for 4x Pad
.............................................. default = 0