Intel 8086-1 Computer Hardware User Manual


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8086
Table 2 Instruction Set Summary (Continued)
Mnemonicand
InstructionCode
Description
76543210 76543210
PROCESSORCONTROL
CLC
e
ClearCarry 11111000
CMC
e
ComplementCarry 11110101
STC
e
SetCarry 11111001
CLD
e
ClearDirection 11111100
STD
e
SetDirection 11111101
CLI
e
ClearInterrupt 11111010
STI
e
SetInterrupt 11111011
HLT
e
Halt 11110100
WAIT
e
Wait 10011011
ESC
e
Escape(toExternalDevice) 11011xxx modxxxrm
LOCK
e
BusLockPrefix 11110000
NOTES
AL
e
8-bit accumulator
AX
e
16-bit accumulator
CX
e
Count register
DS
e
Data segment
ES
e
Extra segment
Abovebelow refers to unsigned value
Greater
e
more positive
Less
e
less positive (more negative) signed values
if d
e
1 then ‘‘to’’ reg if d
e
0 then ‘‘from’’ reg
if w
e
1 then word instruction if w
e
0 then byte instruc-
tion
if mod
e
11 then rm is treated as a REG field
if mod
e
00 then DISP
e
0 disp-low and disp-high are
absent
if mod
e
01 then DISP
e
disp-low sign-extended to
16 bits disp-high is absent
if mod
e
10 then DISP
e
disp-high disp-low
if rm
e
000 then EA
e
(BX)
a
(SI)
a
DISP
if rm
e
001 then EA
e
(BX)
a
(DI)
a
DISP
if rm
e
010 then EA
e
(BP)
a
(SI)
a
DISP
if rm
e
011 then EA
e
(BP)
a
(DI)
a
DISP
if rm
e
100 then EA
e
(SI)
a
DISP
if rm
e
101 then EA
e
(DI)
a
DISP
if rm
e
110 then EA
e
(BP)
a
DISP
if rm
e
111 then EA
e
(BX)
a
DISP
DISP follows 2nd byte of instruction (before data if re-
quired)
except if mod
e
00 and rm
e
110 then EA
e
disp-high
disp-low
Mnemonics
Intel 1978
ifsw
e
01 then 16 bits of immediate data form the oper-
and
ifsw
e
11 then an immediate data byte is sign extended
to form the 16-bit operand
if v
e
0 then ‘‘count’’
e
1 if v
e
1 then ‘‘count’’ in (CL)
x
e
don’t care
z is used for string primitives for comparison with ZF FLAG
SEGMENT OVERRIDE PREFIX
001reg110
REG is assigned according to the following table
16-Bit (w
e
1) 8-Bit (w
e
0) Segment
000 AX 000 AL 00 ES
001 CX 001 CL 01 CS
010 DX 010 DL 10 SS
011 BX 011 BL 11 DS
100 SP 100 AH
101 BP 101 CH
110 SI 110 DH
111 DI 111 BH
Instructions which reference the flag register file as a 16-bit
object use the symbol FLAGS to represent the file
FLAGS
e
XXXX(OF)(DF)(IF)(TF)(SF)(ZF)X(AF)X(PF)X(CF)
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
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