CHAPTER 3 CPU FUNCTIONS
User’s Manual U15109EJ3V0UD
90
(2) Program status word (PSW)
(1/2)
After reset: 00000020H
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
Non-maskable interrupt (NMI) servicing status
0
NMI servicing not under execution.
1
NMI servicing under execution.
This flag is set (1) when an NMI is acknowledged, and disables multiple
interrupts. For details, refer to
7.2.3 NP flag.
EP
Exception processing status
0
Exception processing not under execution.
1
Exception processing under execution.
This flag is set (1) when an exception is generated. Interrupt requests can be
acknowledged when this bit is set. For details, refer to
7.4.3 EP flag.
ID
Maskable interrupt servicing specification
0
Maskable interrupt acknowledgement enabled.
1
Maskable interrupt acknowledgement disabled.
This flag is set (1) when a maskable interrupt request is acknowledged. For
details, refer to
7.3.6 ID flag.
SAT
Note
Saturation detection of operation result of saturation operation instruction
0
Not saturated.
This flag is not cleared (0) if the result of saturated operation instruction execution
is not saturated while this flag is set (1). To clear (0) this flag, write the PSW
directly.
1
Saturated.
CY
Detection of carry or borrow of operation result
0
Overflow has not occurred.
1
Overflow occurred.
OV
Note
Detection of overflow during operation
0
Overflow has not occurred.
1
Overflow occurred.
S
Note
Detection of operation result positive/negative
0
The operation result was positive or 0.
1
The operation result was negative.