The Pangea IC includes an IEEE 1394 FireWire controller with a maximum data rate of 400 Mbits (50MBytes) per second. The Pangea IC provides DMA (direct memory access) support for the FireWire interface.
The controller IC implements the FireWire link layer. A physical layer IC, called a PHY, implements the electrical signalling protocol of the FireWire interface. The PHY supports two FireWire ports by way of external connectors in the I/O bay.
ImportantThe FireWire PHY on the iMac does not operate with external bus power. As long as the computer is plugged into an active AC power outlet, the FireWire PHY is active and the FireWire bus remains connected. If AC power is interrupted, the PHY will not operate.