We can connect PC's together using standard 6 pin connectors (right) or the smaller 4 pin ones (left) as shown in the picture below…
The particular cable I used has a 5 metre length, which exceeds the specifications by 0.5 metres. Even so, I had no problems using it for my test. Increasing the cable length will decrease the connect speed to 200 or 100Mbps, or result in a loss of connectivity.
Connecting a number of computers together involves a daisy chain situation similar to SCSI, but without the hassle of terminators or having to set device ID's.
There are also Firewire hubs available that can be used to connect devices, particularly useful for connecting PC's that have only one Firewire port.
Because Firewire devices run asynchronously, they can be running 100Mbps, 200Mbps and 400Mbps all on the same chain at the same time.