PCI-X Backplane Specification

As far as I know, there is no such thing. I have the PCI-X spec (1.0a) in front of me, and it refers only to PCB implementations. The maximum length for PCI-X 133 is 8 inches - I'll have to look for the 66MHz spec.

Cheers

PeteS

PeteS, 8-inches, then 66Mhz should have longer maximum trace length. Is that the "PCI-X Addendum to the PCI Local Bus" Specification you are saying? BTW, are you familiar with Single board computers(SBC) with one PCI/PCI-x edge connector (i.e for the connection of SBC to Backplane); the length of the overall trace of the PCI is SBC board pci traces+backplane traces right?, What bothers me is that i know the routing guidelines for Add-In card but does that also apply for PCI on motherboard or SBCs?

What revision of the specification do you have? In my copy it says for the PCI 32-bit signals 1.5", for the 64-bit extenstion 2.5"; can you site the information about the 8" (because i'm really having problems keeping up with the length limit).

Ay> > Hi can someone direct me to the PCI-X 66Mhz Backplane Specification, or

The PCI spec can be very confusing.

Lengths are specified two ways:

Motherboard is specified in terms of propagation delay Add-in cards are specified in terms of length on FR4

The add-in card lengths are the minimums for the entire system, incidentally.

Be careful of the signals on 64 bit - the original 32 bit signals still require the standard lengths. In addition, make sure that REQ64 has a

*longer* prop delay than reset to make sure it is valid during the rising edge of reset. If you give them the same prop delays, you can always use a higher value pullup to 'slow' the rising edge, but make sure you avoid the potential race condition.

Cheers

PeteS