What is the difference in firewire 1394a & 1394b connectors?

Question

What is the difference in firewire 1394a & 1394b connectors?

Answer 1

1394a supports up to 400 Mbit/s where as

1394b supports up to 800 Mbit/s

This can make a big difference if one uses a fire wire based external hard disk.

Most of the Notebook seller sites don't mention this information clearly. They just write that the notebook has 1 Firewire 1394 port.

Answer 2

In December of 1995, the Institute of Electrical and Electronics Engineers (IEEE) released an official Firewire specification, dubbed IEEE 1394. This specification, sometimes referred to as 'Firewire 400', describes a hot-swappable peripheral interface with transfer speeds of 100 Mbps, 200 Mbps, and 400 Mbps. During the late 1990s, this standard found its way into Sony electronics (mainly digital camcorders) under the title 'i.LINK'. In January of 1999, Apple released what was probably the first personal computer system to include Firewire ports by default: the Blue PowerMac G3. All Macintosh models from then on have included Firewire connectivity.

Firewire cables come in two variations 4-pin and 6-pin. 6-pin cables provide up to 30V of power, allowing for fully bus-powered devices. 4-pin cables do not provide power.

In April of 2002, the IEEE released an updated Firewire standard, dubbed IEEE 1394b. IEEE 1394b allows for theoretical maximum transfer rates of up to 3.2Gbps. Apple commercially released a subset of this new standard under the title 'Firewire 800' in 2003.

Firewire 800 devices support a maximum transfer speed of around 800Mbps. Firewire 800 adds a new cable type 9-pin cables (also called 'beta' cables), which support the full speed of Firewire 800.

Firewire 800 is backwards-compatible with Firewire 400 when 'bilingual' (9-pin to 6- or 4-pin) cables are used. Firewire 400 devices will still run at Firewire 400 speeds, even when connected to a Firewire 800 host.