Fujitsu MB90460 Series Hardware Manual page 134

■ Interrupt Operation
Figure 7.1-1 shows the activation and return processing for the four types of interrupt functions.
a valid hardware
String type *
instruction being
executed
Fetch the next instruc-
tion and decode
INT instruction?
RETI instruction?
Execute ordinary
instruction
of string type * instruction
Move the pointer to the
next instruction by PC
update
*: When a string type instruction is being executed, the interrupt is evaluated in each step.
Figure 7.1-1 Overall Flow of Interrupt Operation
Main program
Is there
interrupt
request?
Save the dedicated
register on the system
stack
Disable acceptance of
hardware interrupts
(I = 0)
Return the dedicated
register from the system
stack, call the interrupt
routine, and return to
the previous routine
Repetition
completed?
Interrupt activation/return
processing
EI 2 OS?
Software
interrupt/
exception
processing
Hardware
Interrupt
Save the dedicated
register on the system
stack
Update the CPU inter-
rupt processing level
(ILM)
Return
Read the interrupt
processing
vector, update PC and
PCB, and branch to
the interrupt routine
CHAPTER 7 INTERRUPT
EI 2 OS
EI²OS processing
Specified
count terminated?
Alternatively, is there
an end request from the
peripheral
function?
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