UPD17073 NEC, UPD17073 Datasheet - Page 44

• Manufacturer Part Number: UPD17073
• Description: 4-BIT SINGLE-CHIP MICROCONTROLLER WITH HARDWARE FOR DIGITAL TUNING SYSTEM
• Manufacturer: NEC

7.4 Notes on Using ALU
7.4.1 Notes on executing operation to program status word
program status word.
operation executed. However, if the program status word itself is used for an operation, the result of the operation
is stored in the program status word, making it impossible to judge whether a carry or borrow occurs, or the result
of the operation is zero.
the CY and Z flags are set (1) or cleared (0) normally.
7.4.2 Notes on using decimal operation
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(1) Result of addition must be 0 to 19 in decimal.
(2) Result of subtraction must be 0 to 9 or –10 to –1 in decimal.
When an arithmetic operation is performed to the program status word, the result of the operation is stored in the
The CY and Z flags of the program status word are usually set or reset according to the result of an arithmetic
However, if the CMP flag is set, the result of the operation is not stored in the program status word; consequently,
A decimal operation can be executed only if the result of the operation falls within the following range:
If a decimal operation is executed exceeding this range, the CY flag is set, and the result is 1010B (0AH) or higher.
PD17072,17073