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MSM80C154S/83C154S/85C154HVS
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4.7.5.4 Interrupt response time chart when an IE or IP manipulating instruction is
executed after temporarily returning to the main routine from continuous
interrupt processing
If the next interrupt conditions are satisfied during execution of an interrupt processing routine
and the interrupt terminating instruction RETI is then executed and followed by a return to the
main routine where an instruction which manipulates the interrupt enable register (IE) or
interrupt priority register (IP) is executed, the MSM80C154S/MSM83C154S activates the
interrupt mask circuit in the next cycle following execution of the register manipulating
instruction. And if interrupt conditions are met as a result of the re-interrupt mask, the interrupt
address is called in the next cycle. That is, if the instruction executed in the main routine
manipulates either IE or IP, the interrupt address is called after two instructions are executed.
The time chart is shown in Figure 4-52.