[mythtv-users] OT: questions about FireWire

[Mark Knecht]

On Tue, Apr 1, 2008 at 4:24 PM, Jason <spuppet at comcast.net> wrote:
> My biggest question is, the FireWire ports on the cable box
> appear to be host-side ports.  From what I have been
> able to gather, FW uses different connectors for host and
> client, like USB. The ports on the box appear to be the
> bigger host-side ports, and not the smaller client-side
> ports.  So how would I use this with my PC?  All FW cables
> I've looked at have the bigger host-side connector on one
> end and the smaller client-side connector on the other.

Just for clarity there isn't such thing in 1394a or 1394b as a 'host'
or a 'client'. Both 1394 specs are completely bidirectional bus sin
terms of data transfer. The only device that has any priority on the
bus is the one device that is determined to be the root as it decides
how to grant access to the bus to all the other devices. Note that any
1394 device can be root as it's hardware must be designed to handle
this capability and in fact any time there is a bus reset there is a
possibility of a device becoming root.

As for the 4-pin vs 6-pin cables the different is the ability to
transmit or receive bus power. 1394 is a differential signaling bus so
2 wires send data and 2 wires receive it. 6-pin devices may or may not
provide power as they choose. Not all 6-pin 1394 adapter cards supply
power. Some have on-board jumpering to enable sending power. 4-pin
devices neither send nor receive power. Other than the power issue
there isn't any difference between these interfaces.

Be careful that you get the right cables as 1394a and 1394b use
different ones. Most 1394b adapter cards can be directly attached to
1394a devices if you get the right cable. I use both here.

I've had the best luck buying cables online. Hardly worth driving to Frys.

Cheers,
Mark