## ALP Programming Guide and Reference

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### Description

The STI instruction sets the IF. The processor then responds to external interrupts after running the next instruction if the next instruction allows the IF flag to remain enabled. If external interrupts are disabled and the STI instruction is followed by the RET instruction (such as at the end of a subroutine), the RET instruction is allowed to run before external interrupts are recognized. Also, if external interrupts are disabled and the STI instruction is followed by a CLI instruction, which clears the IF flag, then external interrupts are not recognized because the CLI instruction clears the IF flag during its processing.