Interrupt Request Acknowledge Processing Algorithm - NEC mPD780208 Subseries User Manual

Figure 16-12. Interrupt Request Acknowledge Processing Algorithm
Interrupt request
held pending
Yes
among simultaneously generated
Interrupt request
held pending
No
Interrupt request
held pending
××IF:
Interrupt request flag
××MK: Interrupt mask flag
××PR: Priority specification flag
IE: Flag controlling acknowledgment of maskable interrupt request (1 = Enabled, 0 = Disabled)
ISP: Flag indicating priority of interrupt currently serviced (0 = Interrupt with high priority is serviced,
1 = No interrupt request is acknowledged, or interrupt with low priority is serviced)
CHAPTER 16 INTERRUPT AND TEST FUNCTIONS
Yes (high priority)
Any high-
priority interrupt request
××
PR = 0 interrupt
requests?
No
IE = 1?
Yes
Vectored interrupt
servicing
User's Manual U11302EJ4V0UM
Start
No
××IF = 1?
Yes (interrupt request
generation)
No
××MK = 0?
Yes
××PR = 0?
No (low priority)
Any
simultaneously
Yes
generated ×× PR = 0
interrupt
requests?
No
Any
simultaneously
Yes
generated high-priority
interrupt
requests?
No
No
IE = 1?
Yes
No
ISP = 1?
Yes
Vectored interrupt
servicing
Interrupt request
held pending
Interrupt request
held pending
Interrupt request
held pending
Interrupt request
held pending
351