consecutive reads to ensure that the interrupts clear properly. Both the SCSI and DMA interrupt conditions should be handled before leaving the ISR. It is recommended that the DMA interrupt is serviced before the SCSI interrupt, because a serious DMA interrupt condition could influence how the SCSI interrupt is acted upon.

6.When using polled interrupts, go back to Step 1 before leaving the ISR, in case any stacked interrupts moved in when the first interrupt was cleared. When using hardware interrupts, the IRQ/ pin will be asserted again if there are any stacked interrupts. This should cause the system to re-enter the ISR.

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Functional Description

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LSI 53C810A technical manual Functional Description