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The processor interprets the instruction and performs the required action. In general, these actions fall into four categories. MULTIPLE INTERRUPTS The discussion so far has focused only on the occurrenceof a single interrupt. Suppose, however, that multiple interrupts can occur.For example, a program may be receiving data from a communications line andprinting results. The printer will generate an interrupt every time it completes aprint operation. The communication line controller will generate an interrupt everytime a unit of data arrives. The unit could either be a single character or a block,depending on the nature of the communications discipline. In any case, it is possiblefor a communications interrupt to occur while a printer interrupt is being processed.Two approaches can be taken to dealing with multiple interrupts. The first is todisable interrupts while an interrupt is being processed. A disabled interrupt simplymeans that the processor can and will ignore that interrupt request signal. If an interruptoccurs during this time, it generally remains pending and will be checked bythe processor after the processor has enabled interrupts. Thus, when a user programis executing and an interrupt occurs, interrupts are disabled immediately. After theinterrupt handler routine completes, interrupts are enabled before resuming theuser program, and the processor checks to see if additional interrupts have occurred.This approach is nice and simple, as interrupts are handled in strict sequential or
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