CHAPTER 3 CPU FUNCTIONS
User’s Manual U13850EJ4V0UM
77
(2) Program status word (PSW)
Figure 3-4. Program Status Word (PSW)
After reset: 00000020H
Symbol
31
8
7
6
5
4
3
2
1
0
PSW
RFU
NP
EP
ID
SAT
CY
OV
S
Z
RFU
Reserved field (fixed to 0).
NP
Indicates that NMI processing is in progress. This flag is set when NMI is accepted, and
disables multiple interrupts.
EP
Indicates that trap processing is in progress. This flag is set when trap is generated.
Moreover, interrupt requests can be accepted when this bit is sets.
ID
Indicates that accepting external interrupt request is disabled.
SAT
This flag is set if the result of executing saturated operation instruction overflows. If overflow
does not occur, value of previous operation is held.
CY
This flag is set if carry or borrow occurs as result of operation. If carry or borrow does not
occur, it is reset.
OV
This flag is set if overflow occurs during operation. If overflow does not occur, it is reset.
S
This flag is set if the result of operation is negative. It is reset if the result is positive.
Z
This flag is set if the result of operation is zero. If the result is not zero, it is reset.
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