17P012 datasheet(61/320 Pages) RENESAS

61 / 320 page

µPD17012, 17P012

Data Sheet U10101EJ4V0DS

7.4 Notes on Using ALU

7.4.1 Notes on using operations for program status word

If an arithmetic operation is executed for the program status word, the result of the arithmetic operation is

stored in the program status word.

The CY and Z flags of the program status word are set or reset depending on the result of the arithmetic

operation. If an arithmetic operation is executed on the program status word itself, the result of the operation

is stored in the program status word, which makes it impossible to judge occurrence of a carry or a borrow, or

whether the result of the operation is zero.

If the CMP flag is set, however, the result of the operation is not stored in the program status word, and the

CY and Z flags are set or reset normally.

7.4.2 Notes on using decimal operations

A decimal operation can be executed only if the result falls within the following range:

(1) Result of addition:

0 to 19 in decimal

(2) Result of subtraction: 0 to 9 or –10 to –1 in decimal

If a decimal operation is executed exceeding this range, the CY flag is set, and the result is a value greater

than 1010B (0AH).

17P012 Datasheet(PDF) 61 Page - Renesas Technology Corp