8086_instruction_set.html

嵌入式C++开发环境 模拟器 可以帮助你调试开发环境 提高工作效率

</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>label</NOBR>
</FONT>
</TD>
<TD>

Short Jump if first operand is Not Greater and Not Equal to second operand (as set by CMP instruction).
Signed.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
	if SF &lt;> OF then jump
</UL>
</FONT>
Example:<PRE><FONT FACE="Fixedsys">   include 'emu8086.inc'
   #make_COM#
   ORG 100h
   MOV AL, 2
   CMP AL, 3
   JNGE  label1
   PRINT 'AL >= 3.'
   JMP exit
label1:
   PRINT 'Al &lt; 3.'
exit:
   RET</FONT></PRE>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="JNL">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
JNL
</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>label</NOBR>
</FONT>
</TD>
<TD>

Short Jump if first operand is Not Less then second operand (as set by CMP instruction).
Signed.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
	if SF = OF then jump
</UL>
</FONT>
Example:<PRE><FONT FACE="Fixedsys">   include 'emu8086.inc'
   #make_COM#
   ORG 100h
   MOV AL, 2
   CMP AL, -3
   JNL label1
   PRINT 'AL &lt; -3.'
   JMP exit
label1:
   PRINT 'Al >= -3.'
exit:
   RET</FONT></PRE>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="JNLE">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
JNLE
</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>label</NOBR>
</FONT>
</TD>
<TD>

Short Jump if first operand is Not Less and Not Equal to second operand (as set by CMP instruction).
Signed.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
	if (SF = OF) and (ZF = 0) then jump
</UL>
</FONT>
Example:<PRE><FONT FACE="Fixedsys">   include 'emu8086.inc'
   #make_COM#
   ORG 100h
   MOV AL, 2
   CMP AL, -3
   JNLE label1
   PRINT 'AL &lt;= -3.'
   JMP exit
label1:
   PRINT 'Al > -3.'
exit:
   RET</FONT></PRE>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="JNO">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
JNO
</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>label</NOBR>
</FONT>
</TD>
<TD>

Short Jump if Not Overflow.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
	if OF = 0 then jump
</UL>
</FONT>
Example:<PRE><FONT FACE="Fixedsys">; -5 - 2 = -7 (inside -128..127)
; the result of SUB is correct,
; so OF = 0:

include 'emu8086.inc'
#make_COM#
ORG 100h
  MOV AL, -5
  SUB AL, 2   ; AL = 0F9h (-7)
JNO  label1
  PRINT 'overflow!'
JMP exit
label1:
  PRINT 'no overflow.'
exit:
  RET</FONT></PRE>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="JNP">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
JNP
</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>label</NOBR>
</FONT>
</TD>
<TD>

Short Jump if No Parity (odd). Only 8 low bits of result are checked.
Set by CMP, SUB, ADD, TEST, AND, OR, XOR instructions.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
	if PF = 0 then jump
</UL>
</FONT>
Example:<PRE><FONT FACE="Fixedsys">   include 'emu8086.inc'
   #make_COM#
   ORG 100h
   MOV AL, 00000111b   ; AL = 7
   OR  AL, 0           ; just set flags.
   JNP label1
   PRINT 'parity even.'
   JMP exit
label1:
   PRINT 'parity odd.'
exit:
   RET</FONT></PRE>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="JNS">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
JNS
</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>label</NOBR>
</FONT>
</TD>
<TD>

Short Jump if Not Signed (if positive).
Set by CMP, SUB, ADD, TEST, AND, OR, XOR instructions.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
	if SF = 0 then jump
</UL>
</FONT>
Example:<PRE><FONT FACE="Fixedsys">   include 'emu8086.inc'
   #make_COM#
   ORG 100h
   MOV AL, 00000111b   ; AL = 7
   OR  AL, 0           ; just set flags.
   JNS label1
   PRINT 'signed.'
   JMP exit
label1:
   PRINT 'not signed.'
exit:
   RET</FONT></PRE>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="JNZ">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
JNZ
</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>label</NOBR>
</FONT>
</TD>
<TD>

Short Jump if Not Zero (not equal).
Set by CMP, SUB, ADD, TEST, AND, OR, XOR instructions.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
	if ZF = 0 then jump
</UL>
</FONT>
Example:<PRE><FONT FACE="Fixedsys">   include 'emu8086.inc'
   #make_COM#
   ORG 100h
   MOV AL, 00000111b   ; AL = 7
   OR  AL, 0           ; just set flags.
   JNZ label1
   PRINT 'zero.'
   JMP exit
label1:
   PRINT 'not zero.'
exit:
   RET</FONT></PRE>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="JO">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
JO
</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>label</NOBR>
</FONT>
</TD>
<TD>

Short Jump if Overflow.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
	if OF = 1 then jump
</UL>
</FONT>
Example:<PRE><FONT FACE="Fixedsys">; -5 - 127 = -132 (not in -128..127)
; the result of SUB is wrong (124),
; so OF = 1 is set:

include 'emu8086.inc'
#make_COM#
org 100h
  MOV AL, -5
  SUB AL, 127   ; AL = 7Ch (124)
JO  label1
  PRINT 'no overflow.'
JMP exit
label1:
  PRINT 'overflow!'
exit:
  RET</FONT></PRE>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="JP">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
JP
</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>label</NOBR>
</FONT>
</TD>
<TD>

Short Jump if Parity (even). Only 8 low bits of result are checked.
Set by CMP, SUB, ADD, TEST, AND, OR, XOR instructions.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
	if PF = 1 then jump
</UL>
</FONT>
Example:<PRE><FONT FACE="Fixedsys">   include 'emu8086.inc'
   #make_COM#
   ORG 100h
   MOV AL, 00000101b   ; AL = 5
   OR  AL, 0           ; just set flags.
   JP label1
   PRINT 'parity odd.'
   JMP exit
label1:
   PRINT 'parity even.'
exit:
   RET</FONT></PRE>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="JPE">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
JPE
</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>label</NOBR>
</FONT>
</TD>
<TD>

Short Jump if Parity Even. Only 8 low bits of result are checked.
Set by CMP, SUB, ADD, TEST, AND, OR, XOR instructions.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
	if PF = 1 then jump
</UL>
</FONT>
Example:<PRE><FONT FACE="Fixedsys">   include 'emu8086.inc'
   #make_COM#
   ORG 100h
   MOV AL, 00000101b   ; AL = 5
   OR  AL, 0           ; just set flags.
   JPE label1
   PRINT 'parity odd.'
   JMP exit
label1:
   PRINT 'parity even.'
exit:
   RET</FONT></PRE>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="JPO">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
JPO
</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>label</NOBR>
</FONT>
</TD>
<TD>

Short Jump if Parity Odd. Only 8 low bits of result are checked.
Set by CMP, SUB, ADD, TEST, AND, OR, XOR instructions.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
	if PF = 0 then jump
</UL>
</FONT>
Example:<PRE><FONT FACE="Fixedsys">   include 'emu8086.inc'
   #make_COM#
   ORG 100h
   MOV AL, 00000111b   ; AL = 7
   OR  AL, 0           ; just set flags.
   JPO label1
   PRINT 'parity even.'
   JMP exit
label1:
   PRINT 'parity odd.'
exit:
   RET</FONT></PRE>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="JS">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
JS
</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>label</NOBR>
</FONT>
</TD>
<TD>

Short Jump if Signed (if negative).
Set by CMP, SUB, ADD, TEST, AND, OR, XOR instructions.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
	if SF = 1 then jump
</UL>
</FONT>
Example:<PRE><FONT FACE="Fixedsys">   include 'emu8086.inc'
   #make_COM#
   ORG 100h
   MOV AL, 10000000b   ; AL = -128
   OR  AL, 0           ; just set flags.
   JS label1
   PRINT 'not signed.'
   JMP exit
label1:
   PRINT 'signed.'
exit:
   RET</FONT></PRE>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="JZ">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
JZ
</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>label</NOBR>
</FONT>
</TD>
<TD>

Short Jump if Zero (equal).
Set by CMP, SUB, ADD, TEST, AND, OR, XOR instructions.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
	if ZF = 1 then jump
</UL>
</FONT>
Example:<PRE><FONT FACE="Fixedsys">   include 'emu8086.inc'
   #make_COM#
   ORG 100h
   MOV AL, 5
   CMP AL, 5
   JZ  label1
   PRINT 'AL is not equal to 5.'
   JMP exit
label1:
   PRINT 'AL is equal to 5.'
exit:
   RET</FONT></PRE>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="LAHF">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
LAHF
</FONT>
</TD>
<TD>No operands</TD>
<TD>

Load AH from 8 low bits of Flags register.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
	AH = flags register<BR>
</UL>
<PRE><FONT FACE="Fixedsys">
AH bit:   7    6   5    4   3    2   1    0
        [SF] [ZF] [0] [AF] [0] [PF] [1] [CF]</FONT>
</PRE>
bits 1, 3, 5 are reserved.
</FONT>

<BR><BR>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="LDS">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
LDS
</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>
	REG, memory
	</NOBR>
</FONT>
</TD>
<TD>

Load memory double word into word register and DS.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
    <LI>REG = first word</LI>
	<LI>DS = second word</LI>
</UL>
</FONT>
<BR>
Example:
<PRE>
<FONT FACE="Fixedsys">
#make_COM#
ORG 100h

LDS AX, m

RET

m  DW  1234h
   DW  5678h

END
</FONT>
</PRE>
AX is set to 1234h, DS is set to 5678h.
<BR><BR>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="LEA">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
LEA
</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>
	REG, memory
	</NOBR>
</FONT>
</TD>
<TD>

Load Effective Address.
<BR><BR>Algorithm:<BR><BR>
<FONT FACE="Fixedsys">
<UL>
    <LI>REG = address of memory (offset)</LI>
</UL>
</FONT>
<BR>
Generally this instruction is replaced by MOV when assembling when possible.
<BR><BR>
Example:
<PRE>
<FONT FACE="Fixedsys">
#make_COM#
ORG 100h

LEA AX, m

RET

m  DW  1234h

END
</FONT>
</PRE>
AX is set to: 0104h.<BR>
LEA instruction takes 3 bytes, RET takes 1 byte, we start
at 100h, so the address of 'm' is 104h.
<BR><BR>

<FONT FACE="Fixedsys">
<TABLE BORDER=1 NOSHADE>
<TR> <TD>C</TD> <TD>Z</TD> <TD>S</TD> <TD>O</TD> <TD>P</TD> <TD>A</TD> </TR>
<TR> <TD COLSPAN=6>unchanged</TD> </TR>
</TABLE>
</FONT>

			<A NAME="LES">&nbsp;</A>
</TD>
</TR>




<TR>
<TD>
<FONT FACE="Fixedsys">
LES
</FONT>
</TD>
<TD>
<FONT FACE="Fixedsys">
	<NOBR>
	REG, memory
	</NOBR>
</FONT>
</TD>
<TD>