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INSTRUCTION SET DESCRIPTIONS
C-12
DEC Decrement:
DEC
dest
Subtracts one from the destination
operand. The operand may be a byte
or a word and is treated as an
unsigned binary number (see AAA and
DAA).
Instruction Operands:
DEC reg
DEC mem
(dest) ← (dest) – 1 AF
CF –
DF –
IF –
OF
PF
SF
TF –
ZF
Table C-4. Instruction Set (Continued)
Name Description Operation
Flags
Affected
NOTE: The three symbols used in the Flags Affected column are defined as follows:
– the contents of the flag remain unchanged after the instruction is executed
? the contents of the flag is undefined after the instruction is executed
the flag is updated after the instruction is executed