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FireWire |
FireWire is Apple's name for the IEEE 1394 High Speed Serial Bus. It was
initiated by Apple (in 1986) and developed by the IEEE P1394 Working Group,
largely driven by contributions from Apple, although major contributions
were also made by engineers from Texas Instruments, Sony, Digital Equipment
Corporation, IBM, and INMOS/SGS Thomson (now STMicroelectronics).
IEEE 1394 is a serial bus architecture for high-speed data transfer.
Compared to older avionics data buses such as MIL-STD-1553, FireWire is a
serial bus, meaning that information is transferred one bit at a time.
Parallel buses utilize a number of different physical connections, and as
such are usually much less efficient, more costly, and typically heavier.
FireWire fully supports both isochronous and asynchronous applications.
Apple intended FireWire to be a serial replacement for the parallel SCSI bus
while providing connectivity for digital audio and video equipment.
Apple's development began in the late 1980s, later presented to the IEEE,
and was completed in 1995.
As of 2007, IEEE 1394 is a composite of four documents: the original IEEE
Std. 1394-1995, the IEEE Std. 1394a-2000 amendment, the IEEE Std. 1394b-2002
amendment, and the IEEE Std. 1394c-2006 amendment.
On June 12, 2008, all these amendments as well as errata and some technical
updates were incorporated into a superseding standard IEEE Std. 1394-2008.
Apple's internal long-time code-name for FireWire was "Chefcat" starting in
1988 as the team sat around a conference table contemplating what to call
the project and staring at Kliban's famous artwork on Michael Johas Teener's
coffee mug.
That was the "aha" moment articulating the goals of the new
interconnect, at low cost and ultimate simplicity presented to the user to
replace and unify all other PC interconnections and expand beyond that base
to enable ultimate miniaturization of electronics.
The concept of the current loop electronics that became the now pervasive
LVDS was code named "Greyhound" around 1992.
Sony's implementation of the system, "i.LINK", used a smaller connector with
only the four signal circuits, omitting the two circuits which provide power
to the device in favor of a separate power connector.
This style was later added into the 1394a amendment.
This port is sometimes labeled "S100" or "S400" to indicate speed in Mbit/s.
The system is commonly used for connection of data storage devices and DV
(digital video) cameras, but is also popular in industrial systems for
machine vision and professional audio systems.
It is preferred over the more common USB for its greater effective speed and
power distribution capabilities.
Perhaps more important, FireWire uses all SCSI capabilities and has high
sustained data transfer rates, important for audio and video editors.
Benchmarks show that the sustained data transfer rates are higher for
FireWire than for USB 2.0, but lower than USB 3.0.
Results are marked on Apple Mac OS X but more varied on Microsoft Windows.
However, the expensive hardware needed to implement it (US$1–$2) has
prevented FireWire from displacing USB in low-end mass-market computer
peripherals, where product cost is a major constraint.
Under the license offered by MPEG LA, a royalty of US$0.25 per unit is
payable upon the manufacture of each 1394 product. |
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