80C186EC/80C188EC Microprocessor User's Manual

INSTRUCTION SET DESCRIPTIONS
NEG
NOP
NOT
Negate:
When Source Operand is a Byte:
NEG dest
(dest) ← FFH – (dest)
Subtracts the destination operand, (dest) ← (dest) + 1 (affecting flags)
which may be a byte or a word, from 0 When Source Operand is a Word:
and returns the result to the destination.
This forms the two's
(dest) ← (dest) + 1 (affecting flags)
(dest) ← FFFFH – (dest)
complement of the number, effectively
reversing the sign of an integer. If the
operand is zero, its sign is not
changed. Attempting to negate a byte
containing –128 or a word containing –
32,768 causes no change to the
operand and sets OF.
Instruction Operands:
NEG reg
NEG mem
No Operation:
NOP
Causes the CPU to do nothing.
Instruction Operands:
none
Logical Not:
NOT dest
Inverts the bits (forms the one's
complement) of the byte or word
operand.
Instruction Operands:
NOT reg
NOT mem
Table C-4. Instruction Set (Continued)
Name Description Operation
NOTE:
AF ü
CF ü
DF –
IF –
OF ü
PF ü
SF ü
TF –
ZF ü
None AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
When Source Operand is a Byte:
(dest) ← FFH – (dest)
When Source Operand is a Word:
(dest) ← FFFFH – (dest)
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
üthe flag is updated after the instruction is executed
Flags
Affected
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
C-31