[mdlug] [mdlug-admin] IEEE 1394a

[Dan Pritts]

a bit of a late reply here...

On Thu, Jul 17, 2008 at 02:27:55AM -0400, Michael Rudas wrote:
> Actually IEEE-1394*a* is nominally SLOWER than USB 2.0 -- 400 Mbps max
> vs. 480Mbps -- but IEEE-1394*b* has nominally 2x the throughput of the
> "a" version at 800 Mbps.  Real-world results peg 1394a and USB 2.0 as
> about equal; I have not played with the "b" version.

in my experience, 400Mbps firewire is generally faster and definitely
uses less host CPU than USB2, at least under MacOS.   

The reason it never really took off is that apple charged a $1 royalty
on the IP required to make a host adapter or device.   Faced with
USB for free or firewire for a buck, system mfrs. used USB unless
there was a real useful reason for firewire.

the reason it's good for video is because firewire has an "isochronous"
mode, which guarantees a slice of bus bandwidth to a device.  

danno
--
dan pritts
danno at umich.edu
734-929-9770