Firewire Basics - Universal Audio apollo Hardware Manual

FireWire Basics

FireWire (also known as "IEEE 1394" and "i.Link") is a high-speed serial data interconnection protocol that is
used to transfer digital data between devices. FireWire is commonly used to interconnect computer systems to
hard drives, audio interfaces, and digital camcorders. A complete discussion of FireWire is beyond the scope of
this manual, but some of the main points and how they apply to Apollo are covered below.
FireWire vs. USB
FireWire is considered superior to USB for audio purposes because it does not rely on the host processor to
manage low-level data housekeeping (among other reasons). FireWire typically outperforms USB at the same
rated speeds.
FireWire Bus
FireWire devices are connected to a FireWire "bus" which is comprised of all devices in the serial data stream.
The FireWire specification supports up to 63 devices per FireWire bus.
Many FireWire devices and host computers have more than one FireWire connector, but these connectors almost
always attach to the same FireWire bus (most computers do not have more than one FireWire bus). It is possible
to add another FireWire bus to a computer, typically by adding a PCIe-to-FireWire or ExpressCard-to-FireWire
adapter card.
Bus Power
Some FireWire devices can be "bus powered" which means the device derives its operating electricity from the
FireWire bus itself without a power supply of its own. Apollo cannot be bus powered and it does not supply bus
power from its FireWire ports to other devices.
Powering Down
Powering down or disconnecting Apollo when UAD plug-ins are loaded could cause session data loss and/or
unpredictable behavior. Quit all UAD host applications (DAW, Console, UAD Meter & Control Panel) before
disconnecting Apollo.
FireWire 800 vs. FireWire 400
The most common FireWire devices are available in two speeds: FireWire 400 (IEEE 1394a), which supports
transfer speeds up to 400 megabits per second, and FireWire 800 (IEEE 1394b), which supports up to 800
megabits per second. It's usually possible to determine the speed of the FireWire device by the type of FireWire
connector it uses. Apollo is a FireWire 800 device.
FireWire Connectors
FireWire 800 and FireWire 400 devices use different connectors, as illustrated below. This helps to differentiate
between the two device speeds; the connectors are not interchangeable.
FireWire 400 connectors
FireWire 400 devices typically have two types of connector: 4-pin and 6-pin. The small 4-pin FireWire 400
connector is common on digital camcorders and Windows notebook computers. The 6-pin connector is more
common with hard drives and audio devices.
Apollo FireWire Hardware Manual 23 FireWire Basics