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FireWire Ports

The 15-inch PowerBook G4 has one FireWire 400 (IEEE 1394a) port and one FireWire 800 (IEEE 1394b) port. Both FireWire ports

• support booting the system from a mass storage device

• support target disk mode

The two FireWire ports share a single power supply that can provide up to 14 watts total. Both ports are on the same FireWire bus and can connect to up 62 other FireWire devices.

The FireWire hardware and software provided with the 15-inch PowerBook G4 are capable of all asynchronous and isochronous transfers defined by IEEE standard 1394a and 1394b.

For additional information about the FireWire interface and the Apple API for FireWire device control, refer to the resources listed at “FireWire Interface.”

In this section:

FireWire 400 Connector
FireWire 800 Connector
FireWire Device Programming
Target Disk Mode

FireWire 400 Connector

The 6-pin FireWire 400 technology

• supports serial I/O at 100, 200, and 400 Mbps

• provides up to 7 watts of power when the computer system is on or when the power adapter is connected and in sleep mode

The FireWire 400 connector has six contacts, as shown in Figure 3-2. The connector pin assignments are shown in Table 3-2.

When the computer is on or the power adapter is connected, the power pin provides a maximum voltage of 12.8 V (no load) and 7 W power per port. Maximum output current for both ports combined is 1.5 A and is controlled by a self-resetting fuse.

Pin 2 of the 6-pin FireWire connector is ground for both power and the inner cable shield. If a 4-pin connector is used on the other end of the FireWire cable, its shell should be connected to the wire from pin 2.

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 800 Connector

The FireWire 800 port on the 15-inch PowerBook G4 is based on IEEE 1394b and enables a 800 Mbps transfer rate. FireWire 800 uses a 9-pin connector and is backwards compatible with original 1394 FireWire devices with 6-pin or 4-pin connectors. With the appropriate cable, the 9-pin port works seamlessly with legacy FireWire devices. Cables are available to go from both 6-pin and 4-pin connectors to a 9-pin, and 9-pin to 9-pin.

The 9-pin FireWire 800 connector is shown in Figure 3-3. Its connector signals and pin assignments are shown in Table 3-3.

VP (pin 8) provides up to 7 W power, shared with the other FireWire connectors. The voltage on the power pin is approximately 12.8 V.

The 9-pin FireWire 800 port is capable of operating at 100, 200, 400, and 800 Mbps, depending on the device to which it is connected. The FireWire 800 port is bilingual in that it supports both IEEE 1394a and 1394b. Using a cable with a 9-pin connector at one end and a 4-pin or 6-pin connector at the other, the 9-pin port is capable of directly connecting to all existing FireWire devices. Using a cable with 9-pin connectors at both ends, the 9-pin port is capable of operating at 800 Mbps.

The IEEE 1394b standard defines long-haul media using Cat 5 UTP and several kinds of optical fiber. The 15-inch PowerBook G4 is interoperable with such cables but cannot be directly connected to them. To use long-haul cables, connect the computer to a 1394b hub that has the desired kind of long-haul connectors. If the hub has a bilingual port, that port can be connected to any of the computer’s FireWire ports. If the hub has a beta-only port, it can be connected only to the computer’s 9-pin port.

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 15-inch PowerBook G4 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”), 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://developer.apple.com/sdk/.

For additional references, refer to “FireWire Interface.”

Target Disk Mode

One option at boot time is to put the computer into a mode of operation called target disk mode.

When the 15-inch PowerBook G4 is in target disk mode and connected to another Macintosh computer by a FireWire cable, the 15-inch PowerBook G4 operates like a FireWire mass storage device with the SBP-2 (Serial Bus Protocol) standard. Target disk mode has two primary uses:

• high-speed data transfer between computers

• diagnosis and repair of a corrupted internal hard drive

The 15-inch PowerBook G4 can operate in target disk mode as long as the other computer has a FireWire 1394a or 1394b port and is running either Mac OS X (any version) or Mac OS 9 with FireWire software version 2.3.3 or later.

To put the computer into target disk mode, hold down the T key while the computer is starting up. When Open Firmware detects the T key during the boot process, it transfers control to special Open Firmware code.

To take the computer out of target disk mode, press the power button until the computer powers off.

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