What's the difference in these two firewire ports?

Question

Is the speed of the 4 pin IEEE 1394a slower than the 6 pin IEEE 1394a? If not, what's the difference in the two?

Answer 1

FireWire is a proprietary name of Apple Inc. for the IEEE 1394. It is also known as i.Link (Sony’s name) or IEEE 1394. FireWire can connect together up to 63 peripherals.

FireWire 400 can transfer data between devices at 100, 200, or 400 Mbit/s data rates (the actual transfer rates are 98.304, 196.608, and 393.216 Mbit/s, ie 12.288, 24.576 and 49.152MBytes per second respectively).

The 6-pin connector is commonly found on desktop computers and can supply the connected device with power. A 4-pin version is used on many laptops and small FireWire devices and do not have any power connectors, although it is fully compatible with 6-pin interfaces. Some laptops use the 6-pin powered connector, such as Apple's recent offerings.

FireWire 800 (Apple's name for the 9-pin "S800 bilingual" version of the IEEE 1394b standard) was introduced commercially by Apple in 2003. This newer 1394 specification and corresponding products allow a transfer rate of 786.432 Mbit/s with backwards compatibility to the slower rates and 6-pin connectors of FireWire 400.

Although USB 2.0 can theoretically operate at 480 Mbits/s, tests indicate that this speed is rarely attained. This is possibly caused by the client-server architecture of USB, as opposed to the peer-to-peer network operation of FireWire, and the support for memory-mapped devices in the latter, which allows high-level protocols to run without forcing numerous interrupts and buffer copy operations on host CPUs.

Answer 2

They have the same speeds--max 400 Mbps. It's manufacturer's preferences. 1394b is faster (800Mbps) with 9 pins.