Firewire Cable Overview:
With more than 30 times the bandwidth of the popular USB 1.1 peripheral standard, FireWire 400 has been the gold standard for high-speed data transfer. Apple was the first computer manufacturer to include FireWire across its entire product line. Now Apple has upped the ante yet again, effectively doubling data throughput with its implementation of the IEEE 1394b standard, FireWire 800.
FireWire 400 vs. USB 1.x:FireWire
have both found their place in the computer and consumer electronics industries. USB
is the technology of choice for most computer mice, keyboards and other lower bandwidth input devices. FireWire
, with its higher bandwidth, longer distances and much higher-powered bus — is more suitable for such applications as digital video (DV), professional audio, hard drives, high-end digital still cameras and home entertainment devices.
How fast is 1394?
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.
How does 1394 compare to SCSI?
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?
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.
What is hot swapping?
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.