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Columbia ISA |
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Firewire originally was developed by Apple Computer, Inc. as a high speed serial bus. In 1995, a tiny connector showed up on the first DV camcorders shipped by Sony. In late 1995, Firewire was accepted as a standard by the IEEE, henceforth called IEEE 1394. |
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What is
Firewire?
The original FireWire interface, FireWire 400 / 1394a: Firewire is a high-speed serial bus developed by Apple and Texas Instruments that allows for the connection of up to 63 devices. It is widely used for downloading video from digital camcorders to the computer or DVD recorder. Also known as the IEEE 1394 standard, the i.Link connector and the High Performance Serial Bus (HPSB), the first version of FireWire supported 100, 200 and 400 Mbits/sec transfer rates and a distance of 4.5 meters between devices. IEEE 1394b (9-pin) provides 800, 1,600 and 3,200 Mbps speeds, increases cable distance to 100 meters and can use glass or plastic fiber and Cat 5 Ethernet cable. FireWire 800 was the first implementation of 1394b and became available in 2003. Backward compatible with FireWire 400, earlier devices run at the lower speed. Today, you can go to your electronics store and purchase a digital video camcorder. FireWire versus USB 1.1 and USB 2.0 And while USB 2.0 provides a tremendous speed advantage over the older v1.1
USB standard, FireWire remains the high-speed interface performance king for
external devices such as hard drives, DV camcorders and 4X and up DVD
burners/writers. Adaptec.com : Adaptec Firewire 4300 3 port board Many people think Firewire is
Digital Video.
Firewire is much bigger than DV. The Digital VCR Consortium, consisting of more than
50 manufacturers of consumer electronics firms has adopted the
IEEE-1394 High Performance Serial Bus as the standard digital
interface between consumer DV products. Sony's
release of three moderately-priced DV camcorders with 1394 digital
audio/video input/output and device control is a major step in the
widespread adoption of the High Performance Serial Bus for digital
audio/video interconnection. Matsushita (Panasonic) recently joined the 1394 coalition with the Panasonic NV-DE3 DV
camcorder. Other Japanese camcorder and VCR manufacturers are
certain to follow the Sony and Matsushita lead. The Digital Audio/Video
Interoperability Council (DAVIC) and Europe's Digital Video
Broadcast (DVB) consortium have adopted the 1394 bus for set-top box
and other broadcast-related applications. DBS set-top box
manufacturers for the U.S. market appear poised to adopt 1394 in
third-generation satellite TV receivers. What about the wire in the Firewire? As shown in the diagram at the left, the standard Firewire cable actually consists of six wires. Data is sent via two separately-shielded twisted pair transmission lines. The two twisted pairs are crossed in each cable assembly to create a transmit-receive connection. Two more wires carry power (8 to 40 v, 1.5 a max.) to remote devices. Currently, these power lines are rarely used. Sony uses a 4 conductor cable
(called iLink) for the connection to the DV
camcorders. They are like the above mentioned setup, but
without the power wires. They terminate in smaller, 4-prong
connectors. To connect a Sony DV camcorder with a standard
IEE1394 Firewire device or interface card, you need an adapter
cable, 4-prong on one end, 6 on the other. It simply connects the
data lines while omitting the power connection. According to the standard, the IEEE 1394 "wire" is good for 400 Megabits per second over 4.5 meters. The standard cable uses 28 AWG signal pairs with 40 twist/meter. The power pair in the standard cable is 22 AWG. Longer cable runs can be achieved by using thicker cable or by
lowering the bit rate. DV users, keep in mind that the signaling
rate of the Sony DV camcorders is only 100 Megabit per second. Can
it use longer cables? The answer is: Yes. Although way outside of
the spec, several people have reported successful 100 Mbit/sec
transmissions over more than 20 meters using standard cable. There
are also reports of thicker cables being used to span lengths of 30
meters or more at 100 Megabit per second. Assorted Firewire links: Adaptec was one of the first companies with a 1394 Firewire board shipping in volume. Texas Instruments also is one of the Firewire pioneers. Their 1394 chipset was at the core of the world's first 1394 board.
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