PD17012_15 Datasheet, PDF(52/320 Page) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DIGITAL TUNING SYSTEM HARDWARE

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PD17012_15 Datasheet, PDF (52/320 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DIGITAL TUNING SYSTEM HARDWARE

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ÂµPD17012, 17P012

5.8.2 Function of program status word

The program status word is a register that sets the condition of an operation or transfer instruction of the ALU

(Arithmetic Logic Unit) or indicates the result of an executed operation.

Table 5-2 outlines the function of each flag of the program status word.

For details, refer to 7. ALU (Arithmetic Logic Unit) BLOCK.

Table 5-2. Functional Outline of Program Status Word

(RP)

Program status word

(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

This flag modifies the address of the data memory when a data

memory manipulation instruction is executed.

0: No modification

1: Modification

This flag indicates that the result of an arithmetic operation

executed is 0.

Note that the status of 0 or 1 differs depending on the contents of the

compare flag.

This flag indicates the occurrence of a carry or borrow as a result of

execution of an addition or subtraction instruction.

It is reset to 0 if a carry/borrow does not occur; it is set to 1 if a

carry/borrow occurs.

This flag is also used as the shift bit of the âRORC râ instruction.

This flag is used avoid storing the result of an arithmetic operation to

the data memory or general register.

0: Result stored

1: Result not stored

This flag is used to execute an arithmetic operation in decimal.

0: Binary operation executed

1: Decimal operation executed

5.8.3 Notes on using program status word

If an arithmetic operation (addition or subtraction) instruction is executed for the program status word, the

result of the arithmetic operation is stored in the program status word.

For example, even if an operation that causes a carry to occur is executed, if the result of the operation is

0000B, 0000B is stored in the PSW.

5.9 Notes on Using System Register

The data of the system register fixed to 0 is not affected even if a write instruction is executed to it.

This data is always 0 when it is read.

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Data Sheet U10101EJ4V0DS

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