What are IEEE-1394 connectors?
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4-Pin Connector
The 4-pin connector is rectangular in shape, with a small notch or indentation on the bottom edge of the connector shell. A 4-pin connector only carries data, and no power, so it is often found on peripherals that have their own power supplies. This connector type is also commonly found on laptop computers.
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6-Pin Connector
The 6-pin connector is larger than the 4-pin, and is rectangular-shaped with beveled corners on one end. It has flattened contacts that withstand well the rigors of repeatedly connecting and disconnecting. A 6-pin interface provides DC power in addition to the data signals. These interfaces are often found on devices that can provide power, such as a desktop computer.
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9-Pin Connector
9-pin connectors are part of a recent improvement to the IEEE-1394 technology, called FireWire 800 (or IEEE-1394b). The improvement to the specification allows transfer of data at up to twice the speed of the original IEEE-1394 standard. The 9-pin connector is a rectangle with square corners. It has 5 pin contacts on one side, and 4 pin contacts on the other. This new connector type can be adapted to the older 4-pin and 6-pin connector. However, when adapted, the maximum transfer rate will be 400 Mbps. This type of connector is commonly found on Apple® computers.