Technical Q&A's

HW 26 - PCI Type 1 Cycles (15-July-95)

Q Under what circumstances does the Macintosh generate a Type 1 cycle? For machines with a single PCI bus, it seems they are never generated.

A All of Apple's PCI PowerMac CPUs support hierarchical PCI buses. Depending on the PCI bus environment, the PPC host to PCI bridge (Bandit chip) will generate Configuration Type 0 commands to select a device on the PCI bus where the cycle is being run, and Configuration Type 1 commands to select devices behind a PCI-to-PCI bridge. (Multi-Function PCI cards, for example, use a PCI-to-PCI bridge.)

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