
7480 Group and 7481 Group User's Manual
1-50
HARDWARE
1.11 Interrupts
Figure 1.11.8 shows an operation when an interrupt request is accepted.
Figure 1.11.8 Operation When Interrupt Request is Accepted
Stack area
PCL
PCH
S
PS
b0
b7
Interrupt disable flag
Break flag
Note
M(S)
←(PCH)
(S)
←(S)–1
(S)
←(S)–1
M(S)
←(PS)
M(S)
←(PCL)
(S)
←(S)+1
(PCL)
←M(S)
(PS)
←M(S)
(S)
←(S)+1
(S)
←(S)–1
(PCH)
←M(S)
(S)
←(S)+1
Routine being executed
RTI instruction execution
Interrupt service
routine
Contents of program counter
are pushed onto stack
Processing at accepting interrupt
Note: In the case of the BRK instruction interrupt, b4 of PS is set to ‘1’.
Interrupt disable flag ‘0’
→‘1’
Fetch the jump address stored
into vector address
Contents of processor status
register are pulled from stack
Contents of program counter
are pulled from stack
1
Interrupt
request is
generated
3
2
Stack area
PCL
PCH
S
PS
(S)=XXS
Immediately after interrupt
request is accepted
XXS
XXPCH
XXPCL
1
b0
b7
Interrupt disable flag
Break flag
Immediately after system returns
from interrupt service routine
3
XXS
Immediately before interrupt
service routine is executed
Jump address
(from vector address)
XXPCH
XXPCL
XXS–3
(S)=XXS–3
2
(PCL)
(PCH)
(PS)
: Operation performed by software
: Operation automatically performed by hardware
Contents of processor status
register are pushed onto stack
Note
0
1
Note
0
Stack area
PCL
PCH
S
PS
(S)=XXS
XXS
XXPCH
XXPCL
b0
b7
Interrupt disable flag
Break flag
Note
0