|Sun System Handbook - ISO 3.4 June 2011 Internal/Partner Edition|
PCI Local Bus
PCI Mechanical SpecificationPCI boards have two basic form factors, standard or long length (312 mm) and short length (174.63 mm). Variable height short length (119-167 mm) boards are also available. Edge connectors are keyed for 3.3V signaling, 5V signaling, or universal signaling. Universal boards are designed to fit in 3.3V or 5V connectors.
The 32-Bit, 124 pin PCI connector has 120 signal pins and 4 key pins. The 32-Bit connector defines the system signaling as 3.3V or 5V. An optional 64-Bit extension is built into the same connector molding extending the number of pins to 184.
A 32-Bit PCI board identifies itself for 32-Bit transfers when it is installed in a 32-Bit or 64-Bit connector. A 32-Bit PCI board can be installed in either a 32-Bit or 64-Bit connector.
A 64-Bit PCI board identifies itself for 32-Bit transfers when it is installed in a 32-Bit connector. A 64-Bit PCI board identifies itself for 64-Bit transfers when it is installed in a 64-Bit connector.
The signals that enable 64-bit operation are REQ64 and ACK64. They are Side A Pin-60 and Side B Pin-60 of the 32-bit connector.
64-Bit PCI boards do not fit into Ultra 80, Slot 4.
64-Bit PCI boards do not fit into Slots 9 and 10 on A20/A25 System Boards 501-5028, 501-2996, and 501-5270.
PCI Electrical SpecificationThe PCI specification provides for 3.3V and 5V signaling. Signaling is determined by the motherboard. Signaling for a 3.3V PCI board is at 3.3V. Signaling for a 5V PCI board is at 5V. Signaling for a universal PCI board is at 3.3V or 5V.
All PCI connectors require four power rails: +3.3V, +5V, +12V, and -12V. The distinction between a 3.3V and 5V PCI boards is in the signaling protocol, not the connector power rails.
The maximum power allowed for a PCI board is 25 Watts from all four power rails combined.