8088
8086/8088 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
REG is assigned according to the following table:
NOTES:
e
e
0)
16-Bit (w
1)
8-Bit (w
Segment
e
e
e
e
e
AL
AX
CX
DS
ES
8-bit accumulator
16-bit accumulator
Count register
Data segment
Extra segment
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
Above/below refers to unsigned value
Greater
e
less positive (more negative) signed values
more positive:
e
Less
e
e
0 then ‘‘from’’ reg
if d
if w
1 then ‘‘to’’ reg; if d
e
e
0 then byte
1 then word instruction; if w
instruction
Instructions which reference the flag register file as a 16-bit
object use the symbol FLAGS to represent the file:
e
e
if mod
if mod
11 then r/m is treated as a REG field
e
00 then DISP
absent
0*, disp-low and disp-high are
e
FLAGS
X:X:X:X:(OF):(DF):(IF):(TF):(SF):(ZF):X:(AF):X:(PF):X:(CF)
e
e
disp-low sign-extended to
if mod
if mod
01 then DISP
16 bits, disp-high is absent
©
Mnemonics
Intel, 1978
e
e
10 then DISP
disp-high; disp-low
e
e
a
a
a
a
a
a
a
a
if r/m
if r/m
if r/m
if r/m
if r/m
if r/m
if r/m
if r/m
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)
DATA SHEET REVISION REVIEW
The following list represents key differences be-
tween this and the -005 data sheet. Please review
this summary carefully.
a
DISP
DISP
a
a
(DI)
(BP)
(BX)
DISP*
DISP
a
1. The Intel 8088 implementation technology
(HMOS) has been changed to (HMOS-II).
DISP follows 2nd byte of instruction (before data if re-
quired)
e
e
e
then EA disp-high:
*except if mod
disp-low.
00 and r/m
e
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
to form the 16-bit operand
e
e
register
e
1; if v 1 then ‘‘count’’ in (CL)
if v
0 then ‘‘count’’
e
x
don’t care
z is used for string primitives for comparison with ZF FLAG
SEGMENT OVERRIDE PREFIX
0 0 1 reg 1 1 0
30
INTEL [ INTEL ]
