FireWire (IEEE also admits 1394 as i.Link or) is 1986 an interface developed by Apple.

ein 6-Pin FireWire-Stecker
a 6-Pin FireWire plug
FireWire-400-Buchse (unten) und USB-2.0-Buchse  an der Frontseite des Power Macintosh G5
FireWire-400-Buchse (down) and USB-2.0-Buchse at the front side power of the Macintosh G5

originally only on the Macintosh - computers of Apple label name FireWire which can be found can become licensed in the meantime by other companies with the 1394 trade Association. In the PC world FireWire is also well-known as the IEEE 1394 - standard, which was adopted 1995. Sony uses the designation since April 1997 i.LINK for the FireWire interface and an FireWire interface integrated 2 among other things into the PlayStation. The FireWire interface is used predominantly for fast data exchange between computers and Multimedia - or other peripheral devices, however also in industrie and automotive electronics. Originallywhen successor for SCSI develops, FireWire can be used however owing to the high data transmission rate also as alternative to Ethernet (IP of over FireWire).

In the spring 2004 the specification for Wireless FireWire was adopted. She sees an additional Protocol adaptation Layer (PAL)for FireWire over IEEE 802.15.3 forwards. (That is a standard for Wireless personnel AREA network (WPAN)). , Z is planned. B. DVD - To connect Player and sound systems slackly with one another and also with a cable-bound network.

Table of contents

bus structure

maximum are 63 devicesper bus possible, whereby there may not be Ringschluss (first equipment is connected with the latter). With Firewire IEEE1394b Ringschlüsse are permitted. Up to 1.023 penalty can be connected with bridges, so that altogether 64,449 devices can be connected. Thosemaximum length of a S400-Verbindung between two devices amounts to 4.5 M. When using S200 the maximum distance increases to 14 M. With Firewire after IEEE1394b as further connecting kinds network cables, plastic and glass fiber were defined, the one cable length betweenDevices of up to 70 m permit. Differently than that universal Serial bus (USB) permits direct communication of all devices to FireWire among themselves (Peer ton of Peer) without a host (- PC).


original (1995) gave itthe three classes of data signaling rates S100, S200 and S400 for interwirings with the well-known plugs with 6 pins, in addition S25 and S50 for FireWire of baking plan. 2000 were added with IEEE 1394a the 4-polige plugs mentioned by Sony iLink. Furthermore contain IEEE 1394a differentCorrections and increase in efficiency with further maximally S400. Distinguished in the year 2001 Apple of the Academy OF Television kind & Sciences with the technology Emmy for the “important role, those the Firewire technology in the television industry plays”. Since 2002 there is thatSuccessor IEEE 1394b with S800, S1600 and S3200. It introduces a new kind of signaling and new cables with 9-poligen plugs. Since 2003 S800-Hardware is available, which is usually marketed as “FireWire 800”. Also the maximum cable lengthwith 100 m owing to the new coding procedure 8B10B one increased clearly.

data transmission rate

the numbers behind S and/or. ” FireWire “show in each case the approximate transfer rate in Mbit/s. The basic version actually transfers accurately 98.304.000 bits per second(12.288.000 B/s), the successors straight multiple of it. With the SI prefixes usual with transfer rates those are accurate 98,304 kBit/s, while there is with binary prefix accurately 96,000 KiBit /s. In order to come to the round value 96 Mbit/s, would have thus two differentPrefix systems to be combined, as bspw. also with 9 cm disks (1.44 MT = 1440 * 1024 byte). This is gone around in the nomenclature however by the fact that equal the rounded up hundred hundred is indicated. S3200 does not transfer thus exactly 3,200 Mbit/s andalso not 3,200 MiBit /s, but 3,145, 728 MBit/s and/or. 3,000 MiBit /s.

operational areas

is used FireWire today particularly for the transmission of digital pictures (e.g. Industrial camera, FireWire camera) or videos (e.g. Data processing-Camcorder) into a PC, in addition, for the connection of external mass storages such as DVD burner, non removable disks etc. or to the connection of entertainment electronics components, for example with Sony under the name i.LINK and Yamaha with “mLAN “.

Around the data transfer rate of modern non removable disks (over 70MB/s with modern 300GBModels) also in external housings to use to be able the employment of the new 9-poligen Firewire 800 (1394b) is, necessarily there the herkömliche Firewire 400 (1394a) on 400Mbits (USB2: 480 Mbits) limited is, i.e. maximally 50 MB/s to be transferred can. ThisTheoretically possible transfer rate however independently of many Firewire Bridges, which are used in external non removable disk housings, of the plate reached, often only 20MB/s will not become reached Firewire 400 and USB 2,0. With the Firewire 800-Chipsatz Oxford 912 was reported however 70MB/s.An alternative to it would be only external SATA - housings.

equipment addressing and bus management

Firewire do not know a defined central host. Contrary to USB each equipment has the technical facilities to become CONTROLLERs. Knot IDs and task distribution in the bus management become everyoneTimes, if equipment is added or removed to the bus, automatically between all devices negotiated.

The addressing consists of altogether 64 bits and is taken to the standard ISO/CInternational Electronical Commission 13213 (ANSI/IEEE 1212). Of it 10 bits for network IDs (segment IDs) and 6 becomeBit for knot IDs occupies. The remaining 48 bits become the addressing of equipment resources (memory, register,…) used:

Bit 0-9 (10 bits) Bit 10-15 (6 bits) Bit 16-63 (48 bits)
bus ID (segment ID) equipment addressing (knot ID) further addressing

the standard for the coupling of severalBus segments IEEE 1394,1 is not yet adopted, therefore today's hardware uses always only a local bus segment.

The equipment with the highest knot ID of a segment is its roots - knot. It is responsible for asynchronous Arbitration and, as so-called Cycle master, forthe synchronization of all devices for isochronous transmissions. If equipment with appropriate abilities at the bus is present, it furthermore the Isochronous resource gives to managers for the administration of channels and range, the bus manager among other things for optimization of the range, as well asthe power managers for the control of current savings functions.

outstanding features

IEEE 1394a (called by Apple also FireWire 400)

  • 100, 200 or 400 Mbit/s transmission rate
  • of devices can be attached and become with current enterprise automatically recognized: “hotplug " and “hot unplug”
  • current supply for devices (8 to 33 VDC, 1,5A, max.48W) integrated
  • connection over Shielded twisted pair (STP)
    • thin and thus flexible 6-adriges cable (4 veins for Datentransfer, 2 for current supply) or
    • 4-adriges cable (4 veinsnecessarily for Datentransfer, no current supply lines
  • ) no terminators at the cable ends
  • data communication in both directions (bi-directional)
  • 4.5 m max. Distance between 2 devices (with 400 Mbit/s)
  • overall length one “daisy chain “- strand max. 72 m
  • to 63 devices connectablly for each bus(max. 17 at one “daisy chain” - strand)
  • up to 1023 penalty over bridges unitable
  • package-oriented data communication
  • fast isochronous mode
  • equipment addressing automatically (no Jumpereinstellungen at the devices or ID switches necessarily)

IEEE 1394b (called by Apple also FireWire 800)

of characteristicslike 1394a with following extensions and changes:

  • 800 MBit/s transmission rate (later 1,600 and 3,200 Mbit/s)
  • new, 9-adriges cable and new plugs
  • new Arbitrierungsverfahren (minutes) BOSS (bus Ownership/supervisor/Selector)
  • other signal coding and signal level,” beta mode “
  • downward compatibility to 1394a throughpermits bilinguale chips (also enterprise exclusively in the new” beta mode “possible, thus however no more downward compatibility
  • ) the employment of different cable materials (z. B. Glass fiber, UTP)
  • permits longer interwirings (as a function of the cable medium, e.g. 100m when using UTP - cables to S100)


the OHCI specification (open host CONTROLLER interface) contains a mode of operation for FireWire CONTROLLERs, into which FireWire devices can pick or overwrite the main storage out of a computer, without it must be supported by the software on this computer. This makes possibletheoretically large control of the computer by others at the FireWire bus attached participant. At least in the preset configuration among other things Mac OS, Linux , FreeBSD and certain Windows are - versions susceptible. (To source, there see „Slides “.)

Web on the left of

Specifications and trade associations:

article and information pages:

Firewire under Linux:


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