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DEC (DECrement)
<Operation>
Rd – 1 → Rd
<Assembly-Language Format>
DEC Rd
<Examples>
DEC R2L
<Operand Size>
Byte
<Description>
This instruction decrements an 8-bit general register and places the result in the 8-bit general
register.
<Instruction Formats>
Addressing
mode
Register direct
Mnem.
Operands
DEC
Rd
<Condition Code>
I
— — — —
I: Previous value remains unchanged.
H: Previous value remains unchanged.
N: Set to "1" if the result is negative;
otherwise cleared to "0."
Z: Set to "1" if the result is zero; otherwise
cleared to "0."
V: Set to "1" if an overflow occurs (the
previous value in Rd was H'80);
otherwise cleared to "0."
C: Previous value remains unchanged.
Instruction code
1st byte
2nd byte
1
A
0
rd
73
H
N
Z
3rd byte
4th byte
DEC
V
C
—
No. of
states
2
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