Sharp MZ-80B Owner's Manual page 127

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FIGURE 6-0-2
RETURN FROM INTERRUPT CYCLE
HIGHEST PRIORITY PORT
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PORT1A PORT1B PORT 2A PORT 28
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1_ PRIORITY INTERRUPT DAISY CHAIN BEFORE ANY INTERRUPT OCCURS_
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UNDER SERVICE
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2. PORT 2A REQUESTS AN INTERRUPT AND IS ACKNOWLEDGED.
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UNDER SERVICE
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3. PORT 18 INTERRUPTS, SUSPENDS SERVICING OF PORT 2A.
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SERVICE COMPLETE SERVICE RESUMED
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4. PORT 18 SERVICE ROUTINE COMPLETE, "RETI" ISSUED, PORT 2A SERVICE RESUMED.
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5. SECOND "RETI" INSTRUCTION ISSUED ON COMPLETION OF PORT 2A SERVICE ROUTINE .
FIGURE 6.0 -3
DAISY CHAIN INTERRUPT SERVICING