UPD17068 Datasheet, PDF (55/341 Pages) NEC – 4-BIT SINGLE-CHIP MICROCONTROLLER CONTAINING IMAGE DISPLAY CONTROLLER AND PLL FREQUENCY SYNTHESIZER FOR DIGITAL TUNING SYSTEMS

µPD17068
5.8.2 Program Status Word Functions
The program status word is used to set conditions for transfer instructions and operations by the arithmetic
logic unit (ALU), and also to indicate the states of the results of operations.
Table 5-2 outlines the function of each flag of the program status word.
See Chapter 7 for details.
Table 5-2 Outline of Function of Each Flag of Program Status Word
Program status word
(RP)
(PSWORD)
RPL
PSW
b3 b2 b1 b0 b3 b2 b1 b0
BCCZ I
CMY
X
DP
E
Flag name
Index enable flag
(IXE)
Zero flag
(Z)
Carry flag
(CY)
Compare flag
(CMP)
BCD flag
(BCD)
Function
Used to specify whether a data memory address is to be
modified when a data memory manipulation instruction
is executed.
0 : Not modified
1 : Modified
Used to indicate that the result of an arithmetic
operation is 0. Note that the states of 0 and 1 differ,
depending on the value of the compare flag.
Used to indicate the occurrence of a carry or borrow as
the result of an addition or subtraction instruction
executed.
This flag is reset to 0 when neither a carry nor a borrow
is produced.
This flag is set to 1 when a carry or borrow is produced.
This flag is used also as a shift bit for the RORC r
instruction.
Used to specify whether to store the result of an
arithmetic operation in a data memory area or general-
purpose register.
0 : Stores the result.
1 : Does not store the result.
Used to specify whether to perform an arithmetic
operation in decimal.
0 : Performs a binary operation.
1 : Performs a decimal operation.
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