8086 Instruction Set

8086 Instruction Set Summary

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 Add, subtract byte or word
ADC, SBB Add, subtract byte or word and carry (borrow)
INC, DEC Increment, decrement byte or word
NEG Negate byte or word (two's complement)
CMP Compare byte or word (subtract without storing)
MUL, DIV Multiply, divide byte or word (unsigned)
IMUL, IDIV Integer multiply, divide byte or word (signed)
CBW, CWD Convert byte to word, word to double word (useful before multiply/divide)

AAA, AAS, AAM,
AAD
ASCII adjust for addition, subtraction, multiplication, division (ASCII
codes 30-39)
DAA, DAS Decimal adjust for addition, subtraction (binary coded decimal numbers)


Conditional jumps:


JA (JNBE) Jump if above (not below or equal)? +127, -128 range only
JAE (JNB) Jump if above or equal(not below)? +127, -128 range only
JB (JNAE) Jump if below (not above or equal)? +127, -128 range only
JBE (JNA) Jump if below or equal (not above)? +127, -128 range only
JE (JZ) Jump if equal (zero)? +127, -128 range only
JG (JNLE) Jump if greater (not less or equal)? +127, -128 range only
JGE (JNL) Jump if greater or equal (not less)? +127, -128 range only
JL (JNGE) Jump if less (not greater nor equal)? +127, -128 range only
JLE (JNG) Jump if less or equal (not greater)? +127, -128 range only
JC, JNC Jump if carry set, carry not set? +127, -128 range only
JO, JNO Jump if overflow, no overflow? +127, -128 range only
JS, JNS Jump if sign, no sign? +127, -128 range only
JNP (JPO) Jump if no parity (parity odd)? +127, -128 range only
JP (JPE) Jump if parity (parity even)? +127, -128 range only


Loop control:


LOOP Loop unconditional, count in CX, short jump to target address
LOOPE (LOOPZ) Loop if equal (zero), count in CX, short jump to target address
LOOPNE (LOOPNZ) Loop if not equal (not zero), count in CX, short jump to target address
JCXZ Jump if CX equals zero (used to skip code in loop)


Subroutine and Interrupt Instructions


CALL, RET Call, return from procedure (inside or outside current segment)
INT, INTO Software interrupt, interrupt if overflow
IRET Return from interrupt

String Instructions


MOVS Move byte or word string
MOVSB, MOVSW Move byte, word string
CMPS Compare byte or word string
SCAS Scan byte or word string (comparing to A or AX)
LODS, STOS Load, store byte or word string to AL or AX
Repeat instructions (placed in front of other string operations):
REP Repeat
REPE, REPZ Repeat while equal, zero
REPNE, REPNZ Repeat while not equal (zero)

Processor Control Instructions
Flag manipulation:

STC, CLC, CMC Set, clear, complement carry flag
STD, CLD Set, clear direction flag
STI, CLI Set, clear interrupt enable flag
LAHF, SAHF Load AH from flags, store AH into flags
PUSHF, POPF Push flags onto stack, pop flags off stack

Coprocessor, multiprocessor interface:

ESC Escape to external processor interface
LOCK Lock bus during next instruction

Inactive states:

NOP No operation
WAIT Wait for TEST pin activity
HLT Halt processor