expresscard firewire, 800 or 400?

hi, i will buy an expresscard firewire for use my alesis multimix firewire 16(its an external soundcard), i would like to know, if i buy an expresscard firewire 800, can i have a better performance or its the same?
can explain me, whats the diference bettwen 800 and 400 firewire?

if i have an 800 firewire port, can i use firewire hardware witch use 400?

 

Firewire is like usb, it's compatible with older version. So firewire 400 devices work on firewire 800. You'll not get better performance by using a firewire 400 device on a firewire 800 card.

 

thanks for the reply, but can you tell me whats the diference bettwen firewire 800 and 400?

 

"The original release of IEEE 1394-1995[16] specified what is now known as FireWire 400. It can transfer data between devices at 100, 200, or 400 Mbit/s half-duplex data rates (the actual transfer rates are 98.304, 196.608, and 393.216 Mbit/s, i.e. 12.288, 24.576 and 49.152 megabytes per second respectively)[2]. These different transfer modes are commonly referred to as S100, S200, and S400.

Cable length is limited to 4.5 metres (14.8 ft), although up to 16 cables can be daisy chained using active repeaters; external hubs, or internal hubs are often present in FireWire equipment. The S400 standard limits any configuration's maximum cable length to 72 metres (240 ft). The 6-circuit connector is commonly found on desktop computers, and can supply the connected device with power.

The 6-circuit powered connector, now referred to as an alpha connector, adds power output to support external devices. Typically a device can pull about 7 to 8 watts from the port; however, the voltage varies significantly from different devices.[17] Voltage is specified as unregulated and should nominally be about 25 volts (range 24 to 30). Apple's implementation on laptops is typically related to battery power and can be as low as 9 V and more likely about 12 V."

"IEEE 1394b-2002[19] introduced FireWire 800 (Apple's name for the 9-circuit "S800 bilingual" version of the IEEE 1394b standard) This specification and corresponding products allow a transfer rate of 786.432 Mbit/s full-duplex via a new encoding scheme termed beta mode. It is backwards compatible to the slower rates and 6-circuit alpha connectors of FireWire 400. However, while the IEEE 1394a and IEEE 1394b standards are compatible, FireWire 800's connector, referred to as a beta connector, is different from FireWire 400's alpha connectors, making legacy cables incompatible. A bilingual cable allows the connection of older devices to the newer port. In 2003, Apple was the first to introduce commercial products with the new connector.

The full IEEE 1394b specification supports data rates up to 3200 Mbit/s over beta-mode or optical connections up to 100 metres (110 yd) in length. Standard Category 5e unshielded twisted pair supports 100 metres (330 ft) at S100. The original 1394 and 1394a standards used data/strobe (D/S) encoding (renamed to alpha mode) on the circuits, while 1394b adds a data encoding scheme called 8B10B referred to as beta mode."

 

I'm just leaping in here to see if I can gain any info. I run a Tascam FW-1884 firewire device, usually with desktops. It used to work well with an old IBM laptop, and seems OK with a Lenovo recent model under either XP or Vista Business.

I can't get anything to work with either Acer models I have. The Acer 2920 uses a Expresscard. The slot is 54 size the only card I could get was 34. It kept falling out. I've bought a "wing" spacer that helps a lot, but the mechanics are awful.

I use the older 400 1394a devices, which at=re fast enough and I couldn't get the 800 device I bought to work at all.

With my Acers, I'm trying to investigate why they don't work, and would be interested in hearing from anyone else with any experience of firewire diagnostics.

FWIW, most of my adapters are using TI chipsets.

 

FireWire 400 (also known as 1394a) is rated at 400MBps, while FireWire 800 (also known as 1394b) is rated at 800MBps.