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CHAPTER 3 INTERRUPTS
3.4 Interrupt Flow
Figure 3.4-1 shows the interrupt flow.
■ Interrupt Flow
Figure 3.4-1 Interrupt Flow
START
ISE = 1
Yes
Yes
Yes
Yes
No
No
No
No
I & IF & IE = 1
AND
ILM > IL
Fetching and decoding
the next instruction
INT
instruction
Executing an ordinary instruction
Completion
of string instruction
repetition
Updating PC
Saving PS, PC, PCB, DTB,
DPR, and A into the stack
of SSP, and setting ILM = IL
Saving PS, PC, PCB,
DTB, ADB, DPR, and A
into the stack of SSP, and
setting I = O and ILM = IL
S 1
Fetching the interrupt
vector
Executing the extended
intelligent I/O service
I : Flag in CCR
ILM : CPU register level
IF : Internal resource interrupt request
IE : Internal resource interrupt enable flag
ISE : EI
2
OS enable flag
IL : Internal resource interrupt request level
S : Flag in CCR