IEEE 1394 is an interface standard for a serial bus for high-speed communications and isochronous real-time data transfer.

Parallel buses utilize a number of different physical connections, and as such are usually more costly and typically heavier.

Apple intended FireWire to be a serial replacement for the parallel SCSI bus, while providing connectivity for digital audio and video equipment.

On June 12, 2008, all these amendments as well as errata and some technical updates were incorporated into a superseding standard, IEEE Std.

[4] A person or company may review the actual 1394 Patent Portfolio License upon request to MPEG LA.

[15] The 1394 High Performance Serial Bus Trade Association (the 1394 TA) was formed to aid the marketing of IEEE 1394.

[21] During the round, the root node (device nearest the processor) sends a cycle start packet.

Apple's implementation on laptops is typically related to battery power and can be as low as 9 V.[24] An amendment, IEEE 1394a, was released in 2000,[25] which clarified and improved the original specification.

It added support for asynchronous streaming, quicker bus reconfiguration, packet concatenation, and a power-saving suspend mode.

This specification added a new encoding scheme termed beta mode which allowed compliant devices to operate at 786.432 Mbit/s full-duplex.

In 2003, Apple was the first to introduce commercial products with the new connector, including a new model of the Power Mac G4 and a 17" PowerBook G4.

The full IEEE 1394b specification supports data rates up to 3200 Mbit/s (i.e., 400 MB/s) over beta-mode or optical connections up to 100 metres (330 ft) in length.

[27] The Running Disparity calculator attempts to keep the number of 1s transmitted equal to 0s,[28] thereby assuring a DC-balanced signal.

This gives the packet the ability to have at least two 1s, ensuring synchronization of the PLL at the receiving end to the correct bit boundaries for reliable transfer.

In December 2007, the 1394 Trade Association announced that products would be available before the end of 2008 using the S1600 and S3200 modes that, for the most part, had already been defined in 1394b and were further clarified in IEEE Std.

[36] Other future iterations of FireWire were expected to increase speed to 6.4 Gbit/s and additional connectors such as the small multimedia interface.

[37][citation needed] Full support for IEEE 1394a and 1394b is available for Microsoft Windows, FreeBSD,[38] Linux,[39][40] MacOS and NetBSD.

Some FireWire hardware manufacturers also provide custom device drivers that replace the Microsoft OHCI host adapter driver stack, enabling S800-capable devices to run at full 800 Mbit/s transfer rates on older versions of Windows (XP SP2 w/o Hotfix 885222) and Windows Vista.

[46] In Linux, support was originally provided by libraw1394 making direct communication between user space and IEEE 1394 buses.

[50] In June 2010, the FCC issued an order that permitted set-top boxes to include IP-based interfaces in place of FireWire.

[55] IEEE 1394 was the High-Definition Audio-Video Network Alliance (HANA) standard connection interface for A/V (audio/visual) component communication and control.

[56] HANA was dissolved in September 2009 and the 1394 Trade Association assumed control of all HANA-generated intellectual property.

AS5643 is utilized by several large programs, including the F-35 Lightning II, the X-47B UCAV aircraft, AGM-154 weapon and JPSS-1 polar satellite for NOAA.

This is similar to Ethernet networks with the major differences being transfer speed, conductor length, and the fact that standard FireWire cables can be used for point-to-point communication.

This was used for networking until the release of an Ethernet adapter later in the console's lifespan, but very few software titles supported the feature.

This presents operational issues if the camcorder is daisy chained from a faster S400 device or via a common hub because any segment of a FireWire network cannot support multiple speed communication.

The SBP-2 (Serial Bus Protocol 2) used by FireWire disk drives uses this capability to minimize interrupts and buffer copies.

In SBP-2, the initiator (controlling device) sends a request by remotely writing a command into a specified area of the target's FireWire address space.

While this enables high-speed and low-latency communication between data sources and sinks without unnecessary copying (such as between a video camera and a software video recording application, or between a disk drive and the application buffers), this can also be a security or media rights-restriction risk if untrustworthy devices are attached to the bus and initiate a DMA attack.

One of the applications known to exploit this to gain unauthorized access to running Windows, Mac OS and Linux computers is the spyware FinFireWire.