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CHAPTER 6 DETAILED RULES FOR EXECUTION INSTRUCTIONS
6.28 DEC (DECrement Byte Data of General-purpose Register)
Decrement byte data of Ri by one.
■ DEC (DECrement Byte Data of General-purpose Register)
Operation
(Ri) ← (Ri) - 1 (byte subtract)
Assembler format
DEC Ri
Condition code (CCR)
+: Changed by executing instruction
-: Not changed
N: Set to 1 if the MSB is 1 as the result of operation and set to 0 in other cases.
Z: Set to 1 if the result of operation is 00
H
and set to 0 in other cases.
V: Set to 1 if an overflow occurs as the result of operation and set to 0 in other cases.
C: Not changed
Number of execution cycles: 3
Byte count: 1
OP code: D8 to DF
NZVC
+++-