#1: Firewire 400 and 800 are not compatible

So when the world of technology is still in its infancy, and media digital video cameras such as 

the Canon XL-H1 introduced in 2003 start to appear, people automatically 

assume that everything will be able to connect using firewire 400.

But this assumption completely ignores one important thing: firewire 800 was already in existence.

 What we know today as “firewire 400” was so named because it has a transfer speed of up to 400 Mbps.

 Not only did the standard exist before any analog video camera came out, 

but it also has a much smaller native data channel size than firewire 800’s channel size of 1 Gbps.

#2: Firewire 800 is faster than firewire 400

People mistakenly think that because firewire 400 has a transfer speed of up to 400 Mbps, it must be faster than firewire 800.

 But this simply is not true

 During the development of firewire 800, the transfer speed was increased to 10 Gbps which makes it the most powerful and fastest digital interface.

 Firewire 400 was also designed with 10 Gbps in mind, but its size is too large for today’s application so only slower transfer speeds are possible (only 5 Gbps).

Electrical specifications for firewire 800 are available here.

The original IEEE 1394 committee

 intended firewire 400 to be the “experimental” standard, with the option to use it for any data transfers above 100 Mbps.

 However, the final version of firewire 400 was hurriedly developed because of its many uses in digital camcorders and digital still cameras,

 which were already in mass production at the time.

 As a result, it only supports transfer speeds up to 400 MSPS or 10 Gbps (or 2.5 Gbps in certain cases).

The international standard comes under the name IEC 61883 (aka “IEEE 1394-2002 Specification” or “ANSI/IEEE Std 1394-2002” or “JEITA T-106”).

The official standard is available online at the IEEE’s website. 

 even though ANSI is part of the title, it does NOT take part in the development of this standard.

What is the difference between IEEE 1394a and IEEE 1394b?

IEEE 1394 was first ratified as IEEE Std. 1394-1995 (1394a).

 While this standard was still in development, there were already two groups working on the next version of the standard.

 One group followed what SCSI has done, which is to create a series of backward compatible versions of their interface.

 The other group decided to follow the what the USB group has done, 

which is to create a series of completely incompatible versions of their interface.

 This second group formed an alliance with National Semiconductor, who agreed to create silicon for their interface before it was even standardized.

The 1394 series was developed by Sony for their proprietary Firewire hard drives.

 The hard drives are not available for purchase to the public,

 but you can purchase third-party adapters that allow your computer to connect to these drives.

Although the name “1394” is used inside Sony,

 technically it has nothing to do with IEEE 1394 standards because Sony uses a completely different bus architecture called “SNA” (Sony Network Architecture).

 One of the major differences between SNA and IEEE 1394b is because IEEE 1394b requires an external driver while SNA only requires the native driver on the host device.

which statement regarding the firewire standard is accurate ?

The IEEE 1394 standard

 (see IEEE 1394-1995) was proposed in late 1993.

 At that time the IEEE 1394 task force was headed by Dan Licklider,

 chairman of the Personal On-Line Communications Task Force.

 The basic idea behind the 1394 standard is to provide 

a high-speed interconnection for digital peripherals, such as scanners, printers and DV equipment, etc.

 This is to be achieved through the use of an external bus form factor

 which can be easily adapted to host systems ranging from desktop workstations to notebook computers.

This task force gave up after three years because of

 lack of consensus on protocol issues between many manufacturers and lack of interest from others.

In use, FireWire supports a streaming mode, 

where data is read from the host’s device at one-megabit per second,

 and data is written back to the device at a rate of 400 megabits per second. 

In a “transport” mode, a maximum of 400 megabits per second can be achieved by sending data in two directions simultaneously

A maximum speed of 800 megabits per second can be achieved by sending data in four directions simultaneously. 

In all three modes, the bus protocol provides for error checking and correction.

 In addition to error checking and correction, 

this protocol includes support for pattern matching as well as full use of telemetry capabilities.