8086 Instruction Set

The following is a brief summary of the 8086 instruction set:

Data Transfer Instructions

MOV Move byte or word to register or memory

IN, OUT Input byte or word from port, output word to port

LEA Load effective address

LDS, LES Load pointer using data segment, extra segment

PUSH, POP Push word onto stack, pop word off stack

XCHG Exchange byte or word

XLAT Translate byte using look-up table

Logical Instructions

NOT Logical NOT of byte or word (one's complement)

AND Logical AND of byte or word

OR Logical OR of byte or word

XOR Logical exclusive-OR of byte or word

TEST Test byte or word (AND without storing)

Shift and Rotate Instructions

SHL, SHR Logical shift left, right byte or word by 1 or CL

SAL, SAR Arithmetic shift left, right byte or word by 1 or CL

ROL, ROR Rotate left, right byte or word by 1 or CL

RCL, RCR Rotate left, right through carry byte or word by 1 or CL

Arithmetic Instructions ADD, SUB

ADC, SBB

INC, DEC

NEG

CMP

MUL,

DIV IMUL,

IDIV CBW,

CWD

AAA, AAS,

AAM, AAD

DAA, DAS

Add, subtract byte or word

Add, subtract byte or word and carry (borrow) Increment, decrement byte or word

Negate byte or word (two's complement)

Compare byte or word (subtract without storing) Multiply, divide byte or word (unsigned)

Integer multiply, divide byte or word (signed) Convert byte to word, word to double word (useful before multiply/divide)

ASCII adjust for addition, subtraction, multiplication, division (ASCII codes 30-39)

Decimal adjust for addition, subtraction (binary coded decimal numbers)

Transfer Instructions JMP

JA (JNBE) JAE (JNB) JB (JNAE) JBE (JNA) JE (JZ) JG (JNLE) JGE (JNL)

Unconditional jump

Jump if above (not below or"equal) Jump if above or equal (not below) Jump ifbelow (not above or equal) Jump ifbelow or equal (not above) Jump if equal (zero)

Jump if greater (not less or equal) Jump if greater or equal (not less)

JL (JNGE) JLE (JNG) JC, JNC JO, JNO JS, JNS JNP (JPO) Jp (JPE) LOOP

LOOPE (LOOPZ) LOOPNE (LOOPNZ) JCXZ

Jump ifless (not greater nor equal) Jump ifless or equal (not greater) Jump if carry set, carry not set Jump if overflow, no overflow Jump if sign, no sign

Jump if no parity (parity odd) Jump if parity (parity even)

Loop unconditional, count in CX Loop if equal (zero), count in CX

Loop ifnot equal (not zero), count in CX Jump if CX equals zero

Subroutine and Interrupt Instructions

CALL, RET Call, return from procedure

INT, INTO Software interrupt, interrupt if overflow

IRE T Return from interrupt

String Instructions MOVS

MOVSB, MOVSW CMPS

SCAS

LODS, STOS REP

REPE, REPZ REPNE, REPNZ

Move byte or word string Move byte, word string Compare byte or word string Scan byte or word string

Load, store byte or word string Repeat

Repeat while equal, zero Repeat while not equal (zero)

Processor Control Instructions

STC, CLC, CMC Set, clear, complement carry flag

S T D , C L D Set, clear direction flag

S T I, C L I Set, clear interrupt enable flag

LAHF, SAHF Load AH from flags, store AH into flags

PUSHF, POPF Push flags onto stack, pop flags offstack

E S C Escape to external processor interface

LOCK Lock bus during next instruction

NOP No operation (do nothing)

WAIT Wait for signal on TEST input

H L T Halt processor