Firewire Facts

The IEEE 1394 standard is a set of specifications for a high-performance serial bus. The generic IEEE 1394 standard is called HPSB (High Performance Serial Bus). Be aware that some companies market their IEEE 1394-based products under trademarked names, most notably:

  • Firewire, trademarked by Apple Computers, Inc. and the basis of the IEEE 1394 standard
  • i.Link, trademarked by Sony Corporation
  • Lynx, Texas Instruments

Firewire:

  • Uses a serial bus using twisted-pair wiring for data transport.
  • Lets you connect up to 63 devices on one IEEE 1394 bus.
  • Supports many kinds of isochronous devices (devices requiring additional bandwidth to accommodate streaming data), such as digital video cameras and recorders, hard drives, and network adapters.
  • Supports Plug-and-Play and hot-swapping (you can add and remove devices without rebooting).
  • Can provide power (up to certain limits) to devices.
  • Supports peer-to-peer transfers. For example, data can be transmitted between a digital video camera and a recording device without going through a computer.
  • Is supported by Windows 98 and later. Windows NT 4.0 does not support Firewire.

The following table describes the details of common IEEE 1394 standards.

Version / Description
1394 /
  • Supports speeds of 100, 200, 400 megabits per second
  • Maximum cable length is 4.5 meters (15 feet)

1394.A /
  • Clarifies and enhances the original standard.

1394.B /
  • Under development to support speeds of 800, 1600, and 3200 megabits per second
  • Maximum cable length is 100 meters (328 feet)

1394.3 /
  • Supports peer-to-peer data transmission
  • Devices like scanners and digital cameras can send data directly to a printer (no computer involvement required)

You should know the following facts about IEEE 1394:

  • An IEEE 1394 bus does not necessarily include a PC. In other words, various types of devices can potentially act as the root node. The devices on the bus decide the root node each time a device is added or removed from the bus.
  • The maximum number of hops (other devices) between any two devices is 16.
  • You cannot connect IEEE 1394 devices to form a loop.
  • IEEE 1394 devices can be bus powered or self powered.
  • IEEE 1394 cables with four wires are not self-powered; IEEE 1394 cables with six wires are self-powered.

The following cable shows the common IEEE 1394 cables and connectors.

Connector / Cable cross-section

4-pin connector /

6-pin connector /