System Memory Design Guidelines (DDR-SDRAM)
R
160
Intel
®
855PM Chipset Platform Design Guide
6.2.
Intel 855PM MCH DDR Signal Package Lengths
The signals listed in Table 35 are routed with 55
± 15% micro-strip transmission lines. Signals within
the same group are trace length matched within 0.1 mils inside the package. Thus, motherboard routing
does not need to compensate for trace length mismatch in the package for these signals.
Table 35. Intel 855PM Chipset DDR Signal Package Lengths
Data Signal Name
Intel 855PM MCH Package
Trace Length (mils)
Data Signal Name
Intel 855PM MCH Package
Trace Length (mils)
DATA GROUP 1
DATA GROUP 6
SDQ[7:0] 945
SDQ[47:40]
732
SDQS[0] 945 SDQS[5] 732
DATA GROUP 2
DATA GROUP 7
SDQ[15:8] 873 SDQ[55:48]
850
SDQS[1] 873 SDQS[6] 850
DATA GROUP 3
DATA GROUP 8
SDQ[23:16] 765 SDQ[63:56] 950
SDQS[2] 765 SDQS[7] 950
DATA GROUP 4
DATA GROUP 9
SDQ[31:24] 658 SDQ[71:64] 646
SDQS[3] 658 SDQS[8] 646
DATA GROUP 5
SDQ[39:32] 649
SDQS[4] 649
DIFFERENIAL CLOCKS
SCK[5:0] 661 SCK[5:0]#
661
COMMAND – SMA
SMA[0] 462 SMA[7] 515
SMA[1] 441 SMA[8] 446
SMA[2] 481 SMA[9] 523
SMA[3] 537 SMA[10]
404
SMA[4] 434 SMA[11]
536
SMA[5] 548 SMA[12]
538
SMA[6] 510
COMMAND – SBS
SBS[0] 423 SBS[1] 398
