FireWire 800 Connector:
The FireWire 800 port 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.
Note: FireWire adapter cables are not included with the
computer.
The 9-pin FireWire 800 connector signals and pin assignments
are shown in Table 3-3.
Figure 3-3 9-pin FireWire 800 connector : 
| Table 3-3 Signals on the 9-pin FireWire
800 connector |
| Pin |
Signal name |
Description |
| 1 |
TPB- |
Twisted-pair B Minus |
| 2 |
TPB+ |
Twisted-pair B Plus |
| 3 |
TPA- |
Twisted-pair A Minus |
| 4 |
TPA+ |
Twisted-pair A Plus |
| 5 |
TPA
(R) |
Twisted-pair A Ground Reference |
| 6 |
VG |
Power Ground |
| 7 |
SC |
Status Contact (no connection; reserved) |
| 8 |
VP |
Power Voltage (approximately 12.8 V DC) |
| 9 |
TPB (R) |
Twisted-pair B Ground Reference |
|
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 VDC
(nominal).
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 and Data Transfer
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.
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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