Editing USB (section)

=== FireWire (IEEE 1394) ===
At first, USB was considered a complement to FireWire ([[IEEE 1394]]) technology, which was designed as a high-bandwidth serial bus that efficiently interconnects peripherals such as disk drives, audio interfaces, and video equipment. In the initial design, USB operated at a far lower data rate and used less sophisticated hardware. It was suitable for small peripherals such as keyboards and pointing devices.

The most significant technical differences between FireWire and USB include:

* USB networks use a [[star network|tiered-star]] topology, while IEEE&nbsp;1394 networks use a [[tree network|tree]] topology.
* USB&nbsp;1.0, 1.1, and 2.0 use a "speak-when-spoken-to" protocol, meaning that each peripheral communicates with the host when the host specifically requests communication. USB&nbsp;3.0 allows for device-initiated communications towards the host. A FireWire device can communicate with any other node at any time, subject to network conditions.
* A USB network relies on a single host at the top of the tree to control the network. All communications are between the host and one peripheral. In a FireWire network, any capable node can control the network.
* USB runs with a 5&nbsp;[[Volts|V]] power line, while FireWire supplies 12&nbsp;V and theoretically can supply up to 30&nbsp;V.
* Standard USB hub ports can provide from the typical 500&nbsp;mA/2.5&nbsp;W of current, only 100&nbsp;mA from non-hub ports. USB&nbsp;3.0 and USB On-The-Go supply 1.8&nbsp;A/9.0&nbsp;W (for dedicated battery charging, 1.5&nbsp;A/7.5&nbsp;W full bandwidth or 900&nbsp;mA/4.5&nbsp;W high bandwidth), while FireWire can in theory supply up to 60&nbsp;watts of power, although 10 to 20&nbsp;watts is more typical.

These and other differences reflect the differing design goals of the two buses: USB was designed for simplicity and low cost, while FireWire was designed for high performance, particularly in time-sensitive applications such as audio and video. Although similar in theoretical maximum signaling rate, FireWire&nbsp;400 is faster than USB&nbsp;2.0 high-bandwidth in real-use,<ref>{{cite web|title=FireWire vs. USB 2.0|url=http://www.qimaging.com/support/pdfs/firewire_usb_technote.pdf|publisher=QImaging|access-date=20 July 2010|url-status=live|archive-url=https://web.archive.org/web/20101011050049/http://www.qimaging.com/support/pdfs/firewire_usb_technote.pdf|archive-date=11 October 2010}}</ref> especially in high-bandwidth use such as external hard drives.<ref>{{cite web |url= http://www.cwol.com/firewire/firewire-vs-usb.htm |title= FireWire vs. USB&nbsp;2.0 – Bandwidth Tests |access-date= 25 August 2007 |url-status=live |archive-url= https://web.archive.org/web/20070812045719/http://www.cwol.com/firewire/firewire-vs-usb.htm |archive-date= 12 August 2007}}</ref><ref>{{cite web |url=https://www.pricenfees.com/digit-life-archives/usb-2-0-vs-firewire |title=USB&nbsp;2.0 vs FireWire |publisher=Pricenfees |access-date=25 August 2007 |url-status=live |archive-url=https://web.archive.org/web/20161016063120/https://www.pricenfees.com/digit-life-archives/usb-2-0-vs-firewire |archive-date=16 October 2016}}</ref><ref>{{cite magazine |url=https://www.pcmag.com/article2/0,4149,847716,00.asp |title=The Great Interface-Off: FireWire Vs. USB&nbsp;2.0 |magazine=PC Magazine |access-date=25 August 2007 |last=Metz |first=Cade |date=25 February 2003 |url-status=live |archive-url=https://web.archive.org/web/20070930190355/http://www.pcmag.com/article2/0,4149,847716,00.asp |archive-date=30 September 2007 }}</ref><ref>{{cite web|url=http://www.g4tv.com/techtvvault/features/39129/USB_20_Versus_FireWire_pg3.html|title=USB&nbsp;2.0 Versus FireWire|access-date=25 August 2007|author=Heron, Robert|publisher=TechTV|url-status=live|archive-url=https://web.archive.org/web/20070929121843/http://www.g4tv.com/techtvvault/features/39129/USB_20_Versus_FireWire_pg3.html|archive-date=29 September 2007}}</ref> The newer FireWire&nbsp;800 standard is twice as fast as FireWire&nbsp;400 and faster than USB&nbsp;2.0 high-bandwidth both theoretically and practically.<ref>{{cite web | url = http://www.usb-ware.com/firewire-vs-usb.htm | title = FireWire vs. USB&nbsp;2.0 | publisher = USB Ware | access-date = 19 March 2007 | url-status=live | archive-url = https://web.archive.org/web/20070316072513/http://www.usb-ware.com/firewire-vs-usb.htm | archive-date = 16 March 2007}}</ref> However, FireWire's speed advantages rely on low-level techniques such as [[direct memory access]] (DMA), which in turn have created opportunities for security exploits such as the [[DMA attack]].

The chipset and drivers used to implement USB and FireWire have a crucial impact on how much of the bandwidth prescribed by the specification is achieved in the real world, along with compatibility with peripherals.<ref>{{cite web |url=http://www.anandtech.com/mb/showdoc.aspx?i=2602&p=15 |title=Firewire and USB Performance |access-date=1 February 2008 |last=Key |first=Gary |date=15 November 2005 |url-status=live |archive-url=https://web.archive.org/web/20080423214619/http://www.anandtech.com/mb/showdoc.aspx?i=2602&p=15 |archive-date=23 April 2008}}</ref>