Specifications

The power pin provides up to 15 W total power, shared with the other FireWire connectors. The voltage on

the power pin is approximately 25 V.

Pin 2 of the 6-pin FireWire connector is ground return for both power and the inner cable shield. In a FireWire

cable with a 4-pin connector on the other end, the wire from pin 2 is connected to the shell of the 4-pin

connector.

The signal pairs are crossed in the cable itself so that pins 5 and 6 at one end of the cable connect with pins 3

and 4 at the other end. When transmitting, pins 3 and 4 carry data and pins 5 and 6 carry clock; when receiving,

the reverse is true.

FireWire Device Programming

Mac OS X includes general support for the FireWire bus and specific support for various kinds of FireWire

devices and protocols. Developers can use the built-in support or provide additional applications and drivers

for use with their products.

The general FireWire services will configure the FireWire bus, scan the bus for new devices, and allow multiple

drivers and devices to share a single FireWire interface cooperatively. The general services also publish

information about the bus and the devices in the IO Registry, so that IO Kit can match protocols and drivers

to each connected FireWire device.

The specific device and protocol support in Mac OS X as provided with the Power Mac G5 includes the following:

●

General services for Serial Bus Protocol 2 (SBP-2) and support for most mass storage devices using SBP-2,

such as hard disk drives, optical drives, flash card readers, Target Disk Mode (see Target Disk Mode (page

36), and the iPod. Mac OS X can boot from most of these devices.

●

General services for the Audio Video Control (AV/C) protocol and support for most digital video (DV)

cameras and decks using this protocol, including video capture through standard QuickTime APIs.

●

A QuickTime device driver for IIDC/DCAM type cameras such as the iSight.

●

A network device driver supporting IP (Internet Protocol) over FireWire according to IEEE RFC 2734.

●

Additional services for user-space and kernel access to all FireWire resources.

For information on writing FireWire drivers or applications, download the latest FireWire SDK from http://de-

veloper.apple.com/sdk/

Booting from a FireWire Device

The Power Mac G5 computer can boot from a FireWire storage device that implements SBP-2 (Serial Bus

Protocol) with the RBC (reduced block commands) command set.

Input and Output Devices

FireWire Ports