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8086 Instruction Set and its Classification

Published on Oct 23 2009 // 8086 Instruction set

The instructions of 8086 are classified into SIX groups. They are:


  1. DATA TRANSFER INSTRUCTIONS
  2. ARITHMETIC INSTRUCTIONS
  3. BIT MANIPULATION INSTRUCTIONS
  4. STRING INSTRUCTIONS
  5. PROGRAM EXECUTION TRANSFER INSTRUCTIONS
  6. PROCESS CONTROL INSTRUCTIONS

1.DATA TRANSFER INSTRUCTIONS

The DATA TRANSFER INSTRUCTIONS are those, which transfers the DATA from any one source to any one destination.The datas may be of any type. They are again classified into four groups.They are:

GENERAL – PURPOSE BYTE OR WORD TRANSFER INSTRUCTIONS

SIMPLE INPUT AND OUTPUT PORT TRANSFER INSTRUCTION

SPECIAL ADDRESS TRANSFER INSTRUCTION

FLAG TRANSFER INSTRUCTIONS

MOV
PUSH
POP
XCHG
XLAT

 

IN
OUT

LEA
LDS
LES

LAHF
SAHF
PUSHF
POPF

 
2.ARITHMETIC INSTRUCTIONS

These instructions are those which are useful to perform Arithmetic calculations, such as addition, subtraction, multiplication and division.They are again classified into four groups.They are:

ADDITION INSTRUCTIONS

SUBTRACTION INSTRUCTIONS

MULTIPLICATION INSTRUCTIONS

DIVISION INSTRUCTIONS

ADD
ADC
INC
AAA
DAA

SUB
SBB
DEC
NEG
CMP
AAS
DAS

MUL
IMUL
AAM

DIV
IDIV
AAD
CBW
CWD

3.BIT MANIPULATION INSTRUCTIONS

These instructions are used to perform Bit wise operations.

LOGICAL INSTRUCTIONS

SHIFT INSTRUCTIONS

ROTATE INSTRUCTIONS

NOT
AND
OR
XOR
TEST

SHL / SAL
SHR
SAR

ROL
ROR
RCL
RCR

4. STRING INSTRUCTIONS

The string instructions function easily on blocks of memory.They are user friendly instructions, which help for easy program writing and execution. They can speed up the manipulating code.They are useful in array handling, tables and records.

STRING INSTRUCTIONS

REP
REPE / REPZ
REPNE / REPNZ
MOVS / MOVSB / MOVSW
COMPS / COMPSB / COMPSW
SCAS / SCASB / SCASW
LODS / LODSB / LODSW
STOS / STOSB / STOSW

5.PROGRAM EXECUTION TRANSFER INSTRUCTIONS

These instructions transfer the program control from one address to other address. ( Not in a sequence). They are again classified into four groups.They are:

UNCONDITIONAL TRANSFER INSTRUCTIONS

CONDITIONAL TRANSFER INSTRUCTIONS

ITERATION CONTROL INSTRUCTIONS

INTERRUPT INSTRUCTIONS

CALL
RET
JMP

JA / JNBE
JAE / JNB
JB / JNAE
JBE / JNA
JC
JE / JZ
JG / JNLE
JGE / JNL
JL / JNGE

JLE / JNG
JNC
JNE / JNZ
JNO
JNP / JPO
JNS
JO

JP / JPE
JS

LOOP
LOOPE / LOOPZ
LOOPNE / LOOPNZ
JCXZ

INT
INTO
IRET

6.PROCESS CONTROL INSTRUCTIONS

These instructions are used to change the process of the Microprocessor. They change the process with the stored information. They are again classified into Two groups.They are:

FLAG SET / CLEAR INSTRUCTIONS

EXTERNAL HARDWARE SYNCHRONIZATION INSTRUCTIONS

STC
CLC
CMC
STD
CLD
STI
CLI

HLT
WAIT
ESC
LOCK
NOP