Magma PE6R4, PCI Expansion System, PE6RR manual G M a

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2.The 4 and 7 Slot Magma Expansion Systems each add two (2) PCI to PCI Bridges to the PCI Local Bus. The 13 Slot adds three (3) PCI to PCI Bridges to the PCI Local Bus. The PE6R4t adds one (1) bridge. These bridges are the communication paths between the PCI cards and the computer resources. Most computers allow multiple bridges (and thus PCI buses) to be correctly configured. Some computers, unfortunately, place an arbitrary limit on the number of bridge levels that can be traveled during power-on configuration. Your computer “power- on-software” should be PCI Specification 2.1 compliant in order to effectively use a Magma PCI Expansion System. For "fan- out" and "daisy chained" system configurations, where more than one PCI expansion system is being used, you should count all of the bridge levels to your most deeply nested PCI bus to determine the maximum number of bridge levels that must be traveled.

3.For easier understanding, the PCI Local Bus should be viewed as a “Resource Toll road” that runs from the computer CPU (resource home), through the “Toll Booths” (the PCI bridges), to the “Resource Users” (PCI Cards). As in the case of a real Toll Road, the more Toll Booths you have to slow down a “nanosecond” for, the longer it will take you (your data) to get from the PCI Card to the CPU and back again. Under most circumstances the effect cannot even be detected. However, under other conditions, it can be important to know about.

Appendix B Need More Slots? 37