Firewire Tutorial

Firewire, also known as IEEE 1394, is a wired inter-device digital communication standard, providing data rates of up to 400 Mb (megabits) per second. The Firewire standard consists of a serial input/output port and bus, a copper cable capable of carrying both data and power, and the associated software. Its ability to transmit video or audio data in digital form at high speeds, reliably and inexpensively, over cable lengths of up to 14 feet, has made it a popular choice for connecting digital video devices to each other and to computers. The Firewire standard is supported by electronics companies such as Sony, Phillips, Panasonic, Canon, and JVC, as well as computer companies such as Apple, Microsoft, Compaq, and Intel, although many of these companies use the IEEE 1394 label for the technology.

Properties

The Firewire/IEEE 1394 standard has the following properties:

• Consists of both hardware and software specifications
• Completely digital—no conversion to analog
• Data rates of 100, 200, or 400 Mb per second
• Plug and play—connection is automatic once cable is plugged in
• Hot plug-able—cables can be connected and disconnected while in use
• Flexible—supports daisy-chain and branching cable configurations
• Peer-to-peer—can connect digital video recorders (DVRs) to a computer or directly to each other
• Scaleable—can mix 100, 200, or 400 Mb devices on single bus
• Physically easy to use—no special terminators or device IDs to set
• Physically small—thin cables
• Inexpensive
• Non-proprietary—licensing is open and inexpensive
• Two data transfer types—asynchronous and isochronous
  

  • Asynchronous data transfer—The traditional request-and-acknowledge form of computer communication for sending and receiving data.
  • Isochronous data transfer—A continuous, guaranteed data transmission at a pre-determined rate. This allows the transmission of digital video and audio without expensive buffer memory.

History

In the mid 1990’s, Apple Computer invented the Firewire bus for local area networking. At the time it provided connection speeds of 100 Mb per second, although speeds of up to 1000 Mb per second were planned for the future. The standard was soon embraced by computer companies such as Intel and Microsoft, who saw the advantage of the Firewire/IEEE 1394 system over the established USB connection standard for applications such as connecting storage and optical drives. Universal Serial Bus (USB) has a connection speed of only 12 Mb per second. As electronics companies began producing digital video cameras, they too looked to the Firewire standard for connectivity, to maintain an all-digital path for signal quality in digital video editing.

In late 1998, Apple, which held the primary IP for Firewire, began charging a licensing fee of $1 per port–so a hard drive with 2 Firewire ports would cost an extra $2 per unit to construct. While a nuisance in the thriving PC industry, the additional fees would have seriously hampered the future of Firewire in the electronics industry, which typically operates on very thin margins. By the end of 1999, however, the standard was operating under a general licensing group, known as 1394LA, that holds the essential patents relating to the Firewire/IEEE 1394 standard in trust. This is similar to the way in which the patents regarding the MPEG video compression standard are licensed. Companies can now license the IEEE 1394 standard for $0.25 per finished unit, regardless of the number of actual 1394 ports in the unit. The term Firewire, however, remains a trademark of Apple.

The position of Firewire has continued to decline as the performance of USB rises. Apple is not installing Firewire in its latest computers.

More information:*
1394 Trade Association
1394LA Patent Portfolio Group

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