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6
Intel
®
855PM Chipset Platform Design Guide
6.3.
DDR System Memory Interface Strapping .................................................................. 161
6.4.
ECC Disable Guidelines.............................................................................................. 161
6.4.1.
Intel 855PM MCH ECC Functionality Disable ............................................. 161
6.4.2.
DDR Memory ECC Functionality Disable.................................................... 162
6.5.
System Memory Compensation .................................................................................. 162
6.6.
SMVREF Generation................................................................................................... 162
6.7.
DDR Power Delivery ................................................................................................... 162
6.8.
External Thermal Sensor Based Throttling (ETS#)..................................................... 163
6.8.1.
ETS# Usage Model...................................................................................... 163
6.8.2.
ETS# Design Guidelines ............................................................................. 164
6.8.3.
Thermal Sensor Placement Guidelines....................................................... 164
7.
AGP Port Design Guidelines.................................................................................................... 167
7.1.
AGP Interface .............................................................................................................. 167
7.2.
AGP 2.0 Spec.............................................................................................................. 168
7.2.1.
AGP Interface Signal Groups ...................................................................... 168
7.3.
AGP Routing Guidelines ............................................................................................. 169
7.3.1.
1x Timing Domain Routing Guidelines ........................................................ 169
7.3.1.1.
Trace Length Requirements for AGP 1X...................................... 169
7.3.1.2.
Trace Spacing Requirements....................................................... 170
7.3.1.3.
Trace Length Mismatch ................................................................ 170
7.3.2.
2X/4X Timing Domain Routing Guidelines .................................................. 170
7.3.2.1.
Trace Length Requirements for AGP 2X/4X ................................ 170
7.3.2.2.
Trace Spacing Requirements....................................................... 171
7.3.2.3.
Trace Length Mismatch Requirements ........................................ 172
7.3.3.
AGP Clock Skew ......................................................................................... 173
7.3.4.
AGP Signal Noise Decoupling Guidelines................................................... 173
7.3.5.
AGP Routing Ground Reference ................................................................. 174
7.3.6.
Pull-ups ........................................................................................................ 174
7.3.7.
AGP VDDQ and VREF ................................................................................ 176
7.3.8.
VREF Generation for AGP 2.0 (2X and 4X) ................................................ 176
7.3.8.1.
1.5-V AGP Interface (2X/4X) ........................................................ 176
7.3.9.
AGP Compensation ..................................................................................... 176
8.
Hub Interface............................................................................................................................ 177
8.1.
Hub Interface Compensation ...................................................................................... 177
8.2.
Hub Interface Data HI[7:0] and Strobe Signals........................................................... 177
8.2.1.
Internal Layer Routing ................................................................................. 178
8.2.2.
External Layer Routing ................................................................................ 178
8.3.
Hub Interface Data HI[10:8] Signals............................................................................ 179
8.3.1.
Internal Layer Routing ................................................................................. 179
8.3.2.
External Layer Routing ................................................................................ 179
8.3.3.
Terminating HI[11] ....................................................................................... 179
8.4.
HIREF/HI_VSWING Generation/Distribution .............................................................. 179
8.5.
Hub Interface Decoupling Guidelines.......................................................................... 181
9.
I/O Subsystem.......................................................................................................................... 183
9.1.
IDE Interface................................................................................................................ 183
9.1.1.
Cabling......................................................................................................... 183
9.1.2.
Primary IDE Connector Requirements ........................................................ 184
9.1.3.
Secondary IDE Connector Requirements ................................................... 185
9.1.4.
Mobile IDE Swap Bay Support .................................................................... 186
9.1.4.1.
Intel 82801DBM ICH4-M IDE Interface Tri-State Feature............ 186
9.1.4.2.
S5/G3 to S0 Boot Up Procedures for IDE Swap Bay................... 187