Want to know even more about 1394? We've compiled a list of questions and answers designed to satisfy the more technical appetite. If you want to delve deeper into the technology of 1394, we suggest you take advantage of the www.1394ta.org site which has additional technology-related links.

Why was 1394 created?
How many devices can be connected with 1394?
How fast is 1394?
What software do I need?
Can I connect and disconnect devices without turning the power off?
Do I need a computer on the 1394 bus to make it work?
What does a 1394 cable look like?
How does 1394 compare to SCSI?
How does 1394 compare to Ethernet?
Why do most DV camcorders have 4-pin 1394 connectors?
What about the 4.5-meter cable length limitation?
What is a 1394 card?
What does peer-to-peer mean?
What is a 1394 "bus?"
What is a backplane?
What's the difference between DV and 1394?
What's the difference between DV video over 1394, and video captured using a video capture card?
What does daisy chain mean?
What is hot swapping?
What does isochronous mean?
What is the IEEE- Institute of Electrical and Electronics Engineers?
What is the 1394 Trade Association?

Why was 1394 created?     (top)
1394 was designed to be a universal interconnect, eliminating the need for many different input/output connectors. The resulting port integration and consolidation of circuit board space results in an overall reduction in product cost and complexity. The 1394 bus is a versatile, high-speed and inexpensive method of interconnecting a variety of consumer electronics devices and personal computers, while eliminating the frustrating tangle of cables most users encounter today.

How many devices can be connected with 1394?     (top)
With 1394 you can connect up to 63 devices together. When 1394.1 bus bridges become available, it will be possible to connect over 60,000 devices using 1394. Digital camcorders, surround sound processors, scanners, printers, hard disk audio recorders, videoconferencing cameras and disk drives all share a common bus connection, not only to an optional host computer, but to each other as well. Because of this, 1394 is a prime candidate for the "Home Network" standard initiated by VESA (Video Electronic Standards Association) and other industry associations. 

How fast is 1394?     (top)
The 1394 standard defines three signaling rates which, in precise terms, are: 98.304, 196.608 and 393.216 Mbits/s (megabits per second). These rates are referred to in the 1394 standard as S100, S200 and S400. The 1394b specification (finalized in early 2002) expands the standard to include 800 and 1,200 Mbits/s speeds. You can mix and match devices of different speeds on the same bus. Using "isochronous" data transmission, even the S100 implementation supports two simultaneous channels of 30fps (frames per second) broadcast-quality video along with stereo audio.

What software do I need?     (top)
All modern personal computer operating systems already support 1394, including Windows 98, Windows 2000, Windows XP, Mac OS 8.6, and Mac OS 9.0 and 10.0

Can I connect and disconnect devices without turning the power off?     (top)
Yes. 1394 is defined as plug-n-play. That means when you add a new device, the 1394 bus automatically recognizes it. Similarly, when a device is disconnected, the bus automatically reconfigures itself. The standard 1394 cable provides up to 1.5 amps of DC power to keep remote devices "aware," even when they are powered down.

Do I need a computer on the 1394 bus to make it work?     (top)
No, 1394 is peer-to-peer. You do not need a computer to take advantage of 1394. A VCR, for example, can act as a 1394 bus controller for camcorders, TV sets, stereo receivers, amplifiers and other home theater components.

What does a 1394 cable look like?     (top)
1394 interconnections are usually made with a 6-conductor cable that contains two separately shielded "twisted" pairs for transmitting data, plus two power conductors and an overall external shield. The two twisted pairs create a transmit/receive connection. The power conductors (8 to 30VDC, 1.5A) supply power to some devices.

Some devices, such as most digital camcorders, use a smaller 4-pin connector to save space. You can buy a 1394 cable with the 6-pin connector on one end, and the 4-pin connector on the other end in order to connect these devices.

How does 1394 compare to SCSI?     (top)
The SCSI bus requires that devices be serially daisy-chained together, with each device having a non-conflicting, pre-assigned address and that the final SCSI device be terminated. There is a limit of seven devices on a SCSI chain. In contrast, 1394 devices can be connected in multiple configurations. These can include a star or tree pattern with its own daisy chain branches. Device terminators are not required. And 1394 addressing, unlike SCSI, is done dynamically; there is no need for address pre-assignment. Plus, 1394 allows up to 1,023 buses to be bridged together.

How does 1394 compare to Ethernet?     (top)
1394 multiplexes (combines) a variety of different types of digital signals, including video, audio, MIDI and device control commands, on two twisted-pair conductors (similar to that of 10base-T Ethernet). This ability to easily multiplex or combine different signal types distinguishes 1394 from other systems which transmit only a single signal type.

Ethernet, for example, is typically used in data networks and requires special protocols (presently implemented only in proprietary multimedia networking systems) to transmit real-time, high-quality audio and video.

In comparison, 1394 is much more flexible in its accommodation of different data types and topologies than Ethernet and other alternative networking systems. 1394 uses a "fairness" arbitration approach to assure that all devices that have information to transmit get a chance to use the bus. 1394 protocols also include device-specific commands to start and stop camcorders, VCRs and other tasks. Standard Ethernet does not provide these important features.

Why do most DV camcorders have 4-pin 1394 connectors?     (top)
Sony camcorders have only a single 4-pin 1394 connector. It is smaller than the standard 1394 connector and has only the data signaling pairs (no power conductors). The 4-pin 1394 connector is a part of the 1394 standard intended primarily for battery-powered devices.

What about the 4.5-meter cable length limitation?     (top)
1394 cables are limited to 4.5 meters between devices before signal distortion begins to occur. The use of 1394 to implement home networks will require cable hops likely to exceed 10 meters. Restricting the speed of the bus to S200 enables an increase in the distance between nodes to about 14 meters (approximately 45 feet). 1394 transceivers have been announced that are powered by in-wall wiring and extend the distance between active nodes to at least 70 meters using plastic optical fiber (POF). Keep in mind that these distances are "between each device". Multiple devices can be connected so the overall length of the 1394 "network" can be very significant.

What is a 1394 card?     (top)
A 1394 card (or 1394 expansion card, board, or adapter) is add-on circuitry designed to provide 1394 capabilities to a computer that did not originally come with 1394. It consists of a standard-size rigid material (fiberboard or something similar) that plugs into one of the computer's expansion slots in its motherboard (also called the backplane).

What does peer-to-peer mean?     (top)
1394 is a peer-to-peer interface. This allows dubbing from one camcorder to another without the need for a computer. It also allows multiple computers to share a given peripheral without any special support in the peripheral or the computers. It's another important reason why 1394 is the digital interface of choice and why its acceptance is growing.

What is a 1394 "bus?"     (top)
You can think of a bus as a linear electronic path on which several devices share information. As you connect 1394 devices using a common series of cables, you are connecting them to the 1394 bus. (While this kind of bus can actually take you to work - in a manner of speaking - it does not require four wheels.)

What is a backplane?     (top)
A backplane is an electronic circuit board containing circuitry and sockets into which additional electronic devices on other circuit boards or cards can be plugged. In a computer, it is generally synonymous with, or part of, the motherboard.

What's the difference between DV and 1394?     (top)
DV is the actual format of the video that comes out of your digital video camera. It's a super high-resolution format that exceeds the quality of S-VHS. It even has many broadcast professionals thinking about scrapping their BetaCam equipment. The images are crisp, bright and have excellent depth and contrast. Best of all, the information is stored on the video tape in digital form, so it can be copied over and over without any loss.

1394 is the jack and protocol that lets you transfer the DV data to your computer. The full 1394 specification includes frame-accurate device control and the ability to read and write the digital video.

What's the difference between DV video over 1394, and video captured using a video capture card?     (top)
Most of the high-resolution video capture cards on the market use MJPEG compression. The less you compress the video, the better it looks, but the higher the sustained data rate you need. At compression under 6:1 (over 3000 kilobytes/sec) most people will think the video looks as good as the original, but in reality, it will be slightly lower quality. The video will have very slight artifacts and image loss.

In contrast, the DV spec is a 720x480 image size, at roughly a 5:1 compression. More accurately, it is compressed at a constant throughput of 3,600 kilobytes per second which averages out to 5:1 compression.

Quality in. Quality out. What makes DV so special is that when you capture DV footage to your hard drive via 1394, the DV video on your hard drive is an exact digital copy of the original footage. There is no loss. Every 1394 card delivers the exact same DV-quality output. When choosing a 1394 card, there is no video quality debate regardless of the CODEC (compression method) used.

What does daisy chain mean?     (top)
Daisy chaining is a wiring scheme in which one device is wired to another which is wired to another which is wired to another, with the signal passed on from device to device. For example, device A is wired to device B, device B is wired to device C, etc. All devices wired together in this way can receive identical signals or, in contrast to a simple bus, each device in the chain may modify one or more signals before passing them on. 1394 enables the daisy chaining of up to 64 devices which greatly reduces cabling complexity.

What is hot swapping?     (top)
Hot swapping is the connection and disconnection of computer peripherals or other components while a system is turned on, without interrupting system operation. 1394 enables hot swapping.

What does isochronous mean?     (top)
Isochronous data transmission guarantees a certain minimum data rate, such as required for time-dependent data such as video or audio. Think about it. Video and audio occur in continuous streams. If there is a break in the signal for just a moment, the quality of the picture or sound suffers. 1394 is designed to inherently provide isochronous service as required for audio and video communication.

What is the IEEE- Institute of Electrical and Electronics Engineers?     (top)
IEEE is the world's largest technical professional society, based in the USA. Founded in 1884 by a handful of practitioners of the new electrical engineering discipline, today's Institute has more than 320,000 members who participate in its activities in 147 countries. The IEEE sponsors technical conferences, symposia and local meetings worldwide, publishes nearly 25% of the world's technical papers in electrical, electronics, and computer engineering and computer science, provides educational programs for its members and promotes standardization. Areas covered include aerospace, computers and communications, biomedical technology, electric power and consumer electronics.

What is the 1394 Trade Association?     (top)
The 1394 Trade Association was formed in 1994 to facilitate adoption of 1394 by consumer electronics and personal computer manufacturers. Over 300 specifications have been written by the 1394 Trade Association, defining how the technology is implemented in specific applications, such as HDTV's, VCR's, etc. These specifications have been "standardized" by the industry standards organizations such as IEC. In 2002, the 1394 Trade Association will become an official standards organization.

The 1394 Trade Association is an international consortium of 170 companies devoted to the advancement of the IEEE 1394 standards. IEEE 1394 (also known as FireWire and i.LINK) is the digital video link between HDTV's, Digital STBs, Digital VCRs, DVDs, Digital Camcorders as well as PCs and high speed PC peripherals.


For more information please see our web site www.1394ta.org or contact:

1394 Trade Association
1560 East Southlake Blvd., Suite 220
Southlake, TX 76092
USA
Phone: 817-416-2200
Fax: 817-416-2256