8086
Table 2. Instruction Set Summary (Continued)
Mnemonic and
Description
Instruction Code
7 6 5 4 3 2 1 0
7 6 5 4 3 2 1 0
PROCESSOR CONTROL
e
e
e
e
e
CLC
CMC
STC
CLD
STD
Clear Carry
1 1 1 1 1 0 0 0
1 1 1 1 0 1 0 1
1 1 1 1 1 0 0 1
1 1 1 1 1 1 0 0
1 1 1 1 1 1 0 1
1 1 1 1 1 0 1 0
1 1 1 1 1 0 1 1
1 1 1 1 0 1 0 0
1 0 0 1 1 0 1 1
1 1 0 1 1 x x x
1 1 1 1 0 0 0 0
Complement Carry
Set Carry
Clear Direction
Set Direction
e
CLI
STI
Clear Interrupt
Set Interrupt
e
e
HLT
Halt
e
WAIT
Wait
e
ESC
Escape (to External Device)
mod x x x r/m
e
LOCK
Bus Lock Prefix
e
e
NOTES:
if s w
and
if s w
01 then 16 bits of immediate data form the oper-
11 then an immediate data byte is sign extended
e
e
e
e
e
AL
AX
CX
DS
ES
8-bit accumulator
16-bit accumulator
Count register
Data segment
Extra segment
to form the 16-bit operand
e
e
e
1; if v 1 then ‘‘count’’ in (CL)
if v
0 then ‘‘count’’
don’t care
z is used for string primitives for comparison with ZF FLAG
e
x
Above/below refers to unsigned value
e
Less
Greater
e
more positive;
less positive (more negative) signed values
SEGMENT OVERRIDE PREFIX
e
e
1 then word instruction; if w
if d
if w
1 then ‘‘to’’ reg; if d
0 then ‘‘from’’ reg
e
0 0 1 reg 1 1 0
e
0 then byte instruc-
REG is assigned according to the following table:
tion
if mod
if mod
e
e
11 then r/m is treated as a REG field
e
e
e
0)
16-Bit (w
1)
8-Bit (w
Segment
00 then DISP
0*, disp-low and disp-high are
absent
000 AX
001 CX
010 DX
011 BX
100 SP
101 BP
110 SI
111 DI
000 AL
001 CL
010 DL
011 BL
100 AH
101 CH
110 DH
111 BH
00 ES
01 CS
10 SS
11 DS
e
16 bits, disp-high is absent
e
disp-low sign-extended to
if mod
01 then DISP
e
e
disp-high; disp-low
if mod
if r/m
if r/m
if r/m
if r/m
if r/m
if r/m
if r/m
if r/m
10 then DISP
e
e
a
a
a
a
a
a
a
a
000 then EA
001 then EA
010 then EA
011 then EA
100 then EA
101 then EA
110 then EA
111 then EA
(BX)
(SI)
(DI)
(SI)
(DI)
DISP
DISP
DISP
DISP
e
e
e
e
e
e
e
e
e
e
e
e
e
e
(BX)
(BP)
(BP)
(SI)
a
DISP
DISP
DISP*
DISP
a
(DI)
a
a
(BP)
(BX)
Instructions which reference the flag register file as a 16-bit
object use the symbol FLAGS to represent the file:
DISP follows 2nd byte of instruction (before data if re-
quired)
e
FLAGS
X:X:X:X:(OF):(DF):(IF):(TF):(SF):(ZF):X:(AF):X:(PF):X:(CF)
e
e
e
110 then EA disp-high;
*except if mod
disp-low.
00 and r/m
©
Mnemonics
Intel, 1978
DATA SHEET REVISION REVIEW
The following list represents key differences between this and the -004 data sheet. Please review this summa-
ry carefully.
1. The Intel 8086 implementation technology (HMOS) has been changed to (HMOS-III).
2. Delete all ‘‘changes from 1985 Handbook Specification’’ sentences.
30
INTEL [ INTEL ]
