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The main logic board uses the industry-standard peripheral component interconnect (PCI) bus for an I/O expansion bus. It is a 33 MHz bus with 64-bit multiplexed address and data.
The Power Mac G4 also has an AGP graphics slot, which is labeled 1. It accommodates standard 32-bit, 66 MHz AGP-2X cards. The computer is always configured with a graphics card installed in slot 1, so that slot is not available for PCI card expansion. For information about the graphics card, see AGP Graphics Card .
Expansion slots 2, 3, and 4 accommodate 33 MHz PCI cards with either 32-bit or 64-bit address and data buses. The PCI cards can use power at +5 V, +3.3 V, or both. The slots accept standard 6.88-inch and 12.283-inch PCI cards as defined by the PCI Local Bus Specification , Revision 2.1. The cards are required to use the standard ISA fence described in the specification.
The expansion slots support all the required PCI signals and certain optional PCI signals. The PCI slots support the optional 64-bit bus extension signals and cache support signals.
The PCI slots and the AGP slot carry the 3.3V_AUX power and PME signals to allow an expansion card to wake the computer from Sleep mode.
The maximum power available on the AGP slot is 8 watts. The maximum total power available for all three PCI slots is 45 watts.
To install or remove a PCI card, the user first opens the door of the enclosure. Then the user removes the blank PCI fence for the appropriate slot, inserts the card in the slot, and screws the card's fence into place to secure the card. The user then closes the enclosure door and turns on the computer. In order to use the new PCI card, a driver must be installed. The driver installation procedure is documented by the manufacturer of the PCI card in question.
IMPORTANT
The user should first shut down the computer before removing or installing PCI cards. The Power Mac G4 does not support PCI hot-plugging functionality. The main logic board has a red light to let the user know that power is present.
For more information about the PCI expansion slot, refer to Designing PCI Cards and Drivers for Power Macintosh Computers.