77
No
Yes
NMI?
No
Yes
User break?
No
Yes
Level 15
interrupt?
No
Yes
I3 to I0
≤
level 14?
No
Yes
Level 14
interrupt?
No
Yes
Yes
I3 to I0
≤
level 13?
No
Yes
Level 1
interrupt?
No
Yes
I3 to I0 =
level 0?
No
Program
execution state
IRQOUT
low
*
1
Push SR onto stack
Push PC onto stack
IRQOUT
high
*
2
Interrupt?
Copy level of accep-
tance from I3 to I0
Read exception
vector table
Branch to exception
handling routine
I3 to I0: Interrupt mask bits of status register
Notes:
*
1
IRQOUT
is the same signal as the interrupt request signal to the CPU (figure 5.1). The
IRQOUT
pin returns to the high level when the interrupt controller has accepted the
interrupt of a level higher than that specified by bits I3 to I0 in the CPU’s status
register.
*
2 If the accepted interrupt is edge-sensed, the
IRQOUT
pin returns to the high level
when the instruction to be executed by the CPU is replaced by interrupt exception
handling (before the status register is saved to the stack ). If the interrupt controller has
accepted another interrupt of a level higher than the current interrupt, and has sent an
interrupt request to the CPU, however, the
IRQOUT
pin remains low.
Figure 5.2 Flowchart of Interrupt Operation
Содержание HD6417032
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Страница 525: ...490 CK RAS CAS TRp TRc TRcc tRASD1 tRASD2 tCASD3 tCASD2 TRr tCSR Figure 20 18 Self Refresh ...
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