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C-25
INSTRUCTION SET DESCRIPTIONS
JO Jump on Overflow:
JO
disp8
Transfers control to the target location
if the tested condition (OF = 1) is true.
Instruction Operands:
JO short-label
if
(OF) = 1
then
(IP) ← (IP) + disp8 (sign-ext to 16 bits)
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
JP
JPE
Jump on Parity:
Jump on Parity Equal:
JP
disp8
JPE
disp8
Transfers control to the target location
if the tested condition (PF = 1) is true.
Instruction Format:
JP short-label
JPE
short-label
if
(PF) = 1
then
(IP) ← (IP) + disp8 (sign-ext to 16 bits)
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
JS Jump on Sign:
JS
disp8
Transfers control to the target location
if the tested condition (SF = 1) is true.
Instruction Format:
JS short-label
if
(SF) = 1
then
(IP) ← (IP) + disp8 (sign-ext to 16 bits)
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
LAHF Load Register AH From Flags:
LAHF
Copies SF, ZF, AF, PF and CF (the
8080/8085 flags) into bits 7, 6, 4, 2 and
0, respectively, of register AH. The
content of bits 5, 3, and 1 are
undefined. LAHF is provided primarily
for converting 8080/8085 assembly
language programs to run on an 8086
or 8088.
Instruction Operands:
none
(AH) ← (SF):(ZF):X:(AF):X:(PF):X:(CF) 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