FireWire

Firewire was popular in the pro-world. to connect the AD/DA to the PC.

A couple of examples can be found here.

 

It offered a performance USB1 couldn’t match.

Today with USB2/3 performance is not the issue anymore.
Slowly but surely PC’s with a Firewire interface are becoming rare.
USB simply rules.
Even Apple, the one how made Firewire popular is slowly dropping it.
Likewise in the pro-audio world they are switching to USB interfaces.

 

FireWire is Apple's trademark for the IEEE 1394 family of standards. FireWire 400 is "S400" IEEE 1394a and is capable of roughly 400 Mbit/sec and uses the rugged 6-pin socket (not the abominable 4-pin socket). FireWire 800 is "bilingual S800" IEEE 1394b-2002 and uses a 9-pin socket.
Source: Michael Johas Teener

 

FireWire is not jitter free. A good treaty on this subject by Julian Dunn can be found below.

References

Sample clock jitter and real-time audio over the IEEE1394 high performance serial bus -
Julian Dunn, AES 106 May 1999