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Mac OS does not use interrupt acknowledge cycles, but the Macintosh software supports their generation in case some PCI bus chips require them. If a driver needs interrupt acknowledge transactions to control its PCI device, it can use a programming interface that invokes an interrupt acknowledge (read) cycle on the PCI bus. The data returned will be the device's response, traditionally an Intel-style interrupt vector number. The programming interface for interrupt acknowledge cycles is described in Interrupt Acknowledge Cycle Generation.