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MICROPROCESSOR INSTRUCTION REFERENCE->DEC

DEC     Decrement Accumulator or Memory
DECA
DECB
DEC

A <- A - 1 or B <- B - 1 or M <- M - 1

Condition Code Register:

H  Not affected
N  Set if result Negative, else cleared
Z  Set if result Zero, else cleared
V  Set if operand was &80, else cleared
C  Not affected

    

Addressing mode	No of cycles	No of bytes
Inherent:	2	1
Direct:	6	2
Extended:	7	3
Index/Indirect:	6+	2+