MSM80C154S/83C154S/85C154HVS

4.7.5.4Interrupt 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.

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