FireWire, also known as IEEE 1394, is not the kind of cable you’ll typically find these days. Popularized in the early 90s, it has long been a competing standard for USB, not unlike Thunderbolt today. Offering much faster speeds, even faster than USB 2.0, FireWire is the connection you typically find on older external hard drives and digital cameras.
FireWire 800 vs 400
FireWire has two versions, and unlike USB 2.0 and 3.0, they are not backward compatible. They don’t even look alike, which can lead to some confusion. The older standard, FireWire 400, is a flatter connector with one rounded side, while the faster 800 version resembles a fat USB connector.
The naming scheme is accurate as it represents the actual speed of the cable: 400Mbps vs 800Mbps. In comparison, USB 2.0 has 480Mbps and USB 3.0 is completely obsolete at 5Gbps.
Just find your key
Unfortunately for FireWire, currently you will need a FireWire-2018 adapter as much as you need the cable itself. You can find some adapters on Amazon, just make sure it’s the correct type of FireWire as they are not compatible with each other.
You should also avoid using a USB 2.0 adapter if you want to connect FireWire 800 as it will be much slower. Though if that’s the only way to connect it, running at half speed isn’t too bad.