Question - What is the difference between Firewire 1394a and 1394b?
Answer -
Firewire is a high-speed digital interface that comes in two varieties - 1394a (or just 1394) and 1394b. The 1394a standard (Firewire 400) supports data transfer rates up to 400 Mbps and uses a 6-pin connection. The 1394b standard (Firewire 800) can transfer data up to 800 Mbps and uses a 9-pin connection.
An 6-pin to 9-pin adapter can be used to plug a 1394a cable into a 1394b port, but the speed will be limited to 400 Mbps.