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7.91
INT (Software Interrupt)
Store the values of the program counter (PC) and program status (PS) to the stack
indicated by the system stack pointer (SSP) for interrupt processing. Write "0" to the
"S" flag in the condition code register (CCR), to use the "SSP" as the stack pointer for
the following steps. Write "0" to the "I" flag (interrupt enable flag) in the "CCR" to
disable external interrupts. Read the vector table for the interrupt vector number "u8" to
determine the branch destination address, and branch.
This instruction has no delay slot.
Vector numbers 9 to 13, 64 and 65 are used by emulators for debugging interrupts and
therefore the corresponding numbers "INT#9" to "#13", "#64", "#65" should not be used
in user programs.
■ INT (Software Interrupt)
Assembler format:
INT #u8
Operation:
SSP – 4 → SSP
PS → (SSP)
SSP – 4 → SSP
PC + 2 → (SSP)
"0" → I flag
"0" → S flag
(TBR + 3FC
Flag change:
N, Z, V, and C: Unchanged
S and I:
Execution cycles: 3 + 3a cycles
Instruction format:
– u8 × 4) → PC
H
S
I
N
Z
0
0
–
–
Cleared to "0".
MSB
0
0
0
1
CHAPTER 7 DETAILED EXECUTION INSTRUCTIONS
V
C
–
–
1
1
1
1
LSB
u8
187
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