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Chapter 3
CPU Function
Preliminary User’s Manual U15839EE1V0UM00
Figure 3-4:
Program Status Word (PSW)
Note: The result of a saturation-processed operation is determined by the contents of the OV and S
flags in the saturation operation. Simply setting the OV flag (1) will set the SAT flag (1) in a
saturation operation.
Bit Position
Flag
Function
31 to 8
RFU
Reserved field (fixed to 0).
7
NP
Indicates that non-maskable interrupt (NMI) processing is in progress. This flag is set
when NMI is accepted, and disables multiple interrupts.
0: NMI servicing not under execution.
1: NMI servicing under execution.
6
EP
Indicates that exception processing is in progress. This flag is set when an exception is
generated. Moreover, interrupt requests can be accepted when this bit is set.
0: Exception processing not under execution.
1: Exception processing under execution.
5
ID
Displays whether a maskable interrupt request has been acknowledged or not.
0: Interrupt enabled.
1: Interrupt disabled.
4
SAT
Note
Displays that the operation result of a saturated operation processing instruction is sat-
urated due to overflow. Due to the cumulative flag, if the operation result is saturated
by the saturation operation instruction, this bit is set (1), but is not cleared (0) even if
the operation results of subsequent instructions are not saturated. To clear (0) this bit,
load the data in PSW. Note that in a general arithmetic operation, this bit is neither set
(1) nor cleared (0).
0: Not saturated.
1: Saturated.
3
CY
This flag is set if carry or borrow occurs as result of operation (if carry or borrow does
not occur, it is reset).
0: Carry or borrow does not occur.
1: Carry or borrow occurs.
2
OV
Note
This flag is set if overflow occurs during operation (if overflow does not occur, it is
reset).
0: Overflow does not occur.
1: Overflow occurs.
1
S
Note
This flag is set if the result of operation is negative (it is reset if the result is positive).
0: The operation result was positive or 0.
1: The operation result was negative.
0
Z
This flag is set if the result of operation is zero (if the result is not zero, it is reset).
0: The operation result was not 0.
1: The operation result was 0.
31
0
PSW
RFU
After reset
00000020H
8 7
NP
6
EP
5
ID
4
SAT
3
CY
2
OV
1
S Z
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