Firewire 800 and 400 share same bus?

[BrittQ]

FireWire 400 port shares the SAME bus as the FireWire 800 port. So using a FireWire 400 device with a FireWire 800 device connected, slows the FireWire 800 to FireWire 400 speeds.

Is this correct?

 

[BrittQ]

None of you MBP/Tech savvy individuals knows?

 

[robbm]

That's certainly my understanding, but only from various forum posts. I'm still looking for an authoritative source to confirm it.

Apple's documentation does confirm that they share the same bus, but it doesn't appear to confirm what the implications of this are.

My understanding is that if you use a FW800 hub (or if you daisy-chain any FW400 devices off FW800 devices) then the bus will run at full speed. But again I don't have an authoritative source for this.