How FireWire Works

FireWire is most associated with digital video, while its main purpose is to connect different pieces of equipment in order to facilitate in sharing information. FireWire was created based on lines very similar to USB or Universal Serial Bus. This new interface was built to transfer information between digital devices, video and audio equipments to be more precise. FireWire can also be termed as IEEE 1394. It is extremely fast, with speeds up to 800 Mbps. Manufacturers are working hard to enhance the speed further up to an unbelievable 3.2 Gbps. At any given time, up to 63 devices can be connected through FireWire bus. It is easy to configure with any operating system and both Windows OS and Mac OS support it.

The Working

• Through the process of enumeration, when the computer is turned on, it automatically detects all the devices connected to it and assigns each of these devices with an address. With FireWire, the operating system automatically detects the connected devices and asks for the driver disc.
• If the device is already installed, then the computer automatically begins exchanging information with the device.
• FireWire devices have the ability to be connected or disconnected, irrespective of the power on.
• FireWire also uses peer-to-peer technology which allows the two FireWire devices to communicate without connecting through a computer.


The original FireWire 400 (1394a) showcased the transfer rates of up to 400 Mbps and the cable length between the two devices required was 4.5 meters. However, the launch of new FireWire 800 (1394b) showcased a much faster version of transfer speeds up to 800 Mbps, while the cable length between devices could be 100 meters. While FireWire was much faster than USB 2.0 (which gives transfer speed of 480 Mbps and 5 meters cable length), its implementation was costlier. Hence, most companies adapted USB 2.0 as the standard connecting interface.

Other Key Features

FireWire devices have the ability to draw their power from the connection itself; hence, even unpowered devices can work. The cable used for connecting the devices comprises of two power conductors with an ability to supply power of up to 8 to 30 volts and 1.5 amps to the unpowered devices. Along with this, two twisted pair sets aim to carry the data to and fro using a 6-pin configuration. Smaller FireWire devices, though, can work with only 4-pin connectors and hence they are more space saving. FireWire 800 has an ability to become compatible with FireWire 400 as well. Hence, adapters that are able to allow both the combinations are available.

The standard 64-bit addressing module, based on IEEE 1212 standards, is used by FireWire. Each information packet is divided into three parts as sent by device to the FireWire: 10-bit bus ID that helps determine which FireWire bus sent the data; 6-bit physical ID that helps identify the device on the bus that sent the data; and 48-bit storage area, that has the ability to address up to 256 terabytes of information for each node. In total, 64,000 nodes can be allowed on a system.

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