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CHAPTER 2 CPU

2.8.4 Interrupt Stack

The interrupt stack is the area indicated by the system stack pointer (SSP). The PC or

PS value is saved to it or restored from it. After an interrupt is caused, the PC value is

stored at the address indicated by the SSP and the PS value is stored at the address

"SSP + 4."

Interrupt Stack

Figure 2.8.1 shows an example of the interrupt stack.

Figure 2.8-1 Example of Interrupt Stack

80000000
H
7FFFFFF8
H
80000000
H
80000000
H
7FFFFFFC
H
7FFFFFFC
H
7FFFFFF8
H
7FFFFFF8
H
SSP SSP
Memory Memory
[Before interrupt] [After interrupt]
P
P
S
C