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CHAPTER 21 INTERRUPT AND TEST FUNCTIONS
Table 21-4. Interrupt Request Enabled for Multiple Interrupt During Interrupt Servicing
Maskable Interrupt Request
PR = 0 PR = 1
IE = 1 IE = 0 IE = 1 IE = 0
Non-maskable interrupt D D D D D
ISP=0 E E D D D
ISP=1 E E D E D
Software interrupt E E D E D
Remarks 1. E : Multiple interrupt enable
2. D :Multiple interrupt disable
3. ISP and IE are the flags contained in PSW
ISP=0 : An interrupt with higher priority is being serviced
ISP=1 : An interrupt request is not accepted or an interrupt with lower priority is
being serviced
IE=0 : Interrupt request acknowledge is disabled
IE=1 : Interrupt request acknowledge is enabled
4. PR is a flag contained in PR0L, PR0H, and PR1L
PR=0 : Higher priority level
PR=1 : Lower priority level
Interrupt Currently
Being Processed
Non-maskable
Interrupt
Request
Multiple Interrupt
Request
Maskable interrupt