[wellylug] FYI: Firewire vs USB2

[Andrew]

The recent thread on the USB HD got me thinking about USB vs Firewire.  
I found this (Mac orientated) item.

They're talking FireWire 400 vs USB 2 High Speed.

FireWire's advantages:
1. Guaranteed Bandwidth. The bandwidth is *guaranteed* as every device 
connected to the FireWire bus can transfer up to 40 MB/sec.  USB 2's 
speeds drop when more devices are connected.  This is critical for 
Desktop Video as DV software, like iMovie, does not handle speed 
drop-offs well, it causes lost frames and glitchy DV footage.  You 
can't have variable speed for DV connections.

2. Transfer speed. FireWire runs at 40MB/Sec continuously (assuming the 
device connected can push that much data), USB 2's 48MB transfer speed 
is "burst" speed, the highest momentary peak it can handle.

3. FireWire supplies power to devices. The FireWire bus can power 
devices needing up to 15 volts of power, so that means that compact 
"pocketable" hard drives can be powered by the FireWire bus, whereas 
USB 2 portable drives need an external power brick.  This is why the 
iPod can be charged by the computer it's connected to, as it uses 
FireWire.  If the iPod used USB 2, it would require a separate AC 
adapter to recharge the battery.

4. Bootable. FireWire is bootable, USB 2 (and USB 1) are not.  You can 
have a pocket-drive with you (with a good copy of your OS and 
diagnostic software on it) so you have a backup hard drive to use both 
for data storage and to boot off from in order to run diagnostics and 
repairs.

5. Shared Bus. USB 2 and USB 1 devices are connected to the same bus, 
whereas FireWire is on its own bus.  There will be less "traffic" to 
slow down the FireWire signals.  In fact, FireWire 400 and FireWire 800 
are on separate buses themselves, even though FireWire 800 is backwards 
compatible with FireWire 400.

USB 2 in and of itself isn't bad, it's just not made to compete 
directly with FireWire.  FireWire is consistent in its throughput, 
supplies power to portable devices, eliminating the need for AC 
adapters, and is boot-able.

USB 2 does have some advantages as well:
It's faster than USB 1, which makes it good for scanners, printers, and 
light use of hard drives.  It's backwards compatible with USB 1.  USB 2 
devices work fine with USB 1, just slower (FireWire 800 is backwards 
compatible too, but requires a cable adapter to use FireWire 400 cables 
with FireWire 800).

The two technologies are designed to compliment each other, not fight 
with each other.  Yes, there is some overlap between them, as both can 
handle decent throughput on hard drives and optical drives.  However, 
there are still some areas in which FireWire is superior, guaranteed 
bandwidth, supplying power to portable devices, and being boot-able.

Cheers
Andrew
--  
zrx1100 at paradise.net.nz
http://zrx.homeip.net/index.html