Firewire was initiated by Apple and develop by many companies such Texas Instrument, IBM, Sony, STMicroelectronic and Digital Equipment Corporation join in IEEE project and they release IEEE 1394. Firewire is a fastest serial data transfer today, most used type of firewire is firewire 400 and 800. Firewire 400 aka IEEE1394a claims the speed about 400MBit/s half duplex and firewire 800 aka IEEE1394b claims the speed about 786.432 Mbits/s full duplex. Some old device use firewire 400 and the new device use firewire 800 and became a problem when you want to connect firewire 800 to 400.
Firewire 800 standardized 9 circuit connector and firewire 400 standardized 6 circuit connector. Many new laptop especially new Mac use firewire 800 and you want to connect your device that use firewire 400 such hardrive, camcorder or many more. Totally you can’t connect it directly and you must need firewire 800 to 400 adapter to solve the problem. It solves the connecter from 9 to 6 and synchronizes the data transfer so you can easily connect your firewire 800 to 400. You can buy it from electronic shop that sell computer peripheral and the price is about $4 – $20, and to make sure you can see the price and the detail at Amazon.