Data Transfer Instructions

MOV

Movebyteor wordXCHG

Exchangebyteor wordXLAT

TranslatebyteLEA

LoadeffectiveaddressLOS

LoadpointerusingOSLES

LoadpointerusingES

Addition Arithmetic InstructionsAOD

Addbyteor wordADC

Add byteor word withcarryINC

Incrementbyteor word by1AAA

ASCII adjustfor additionDAA

Decimaladjustfor addition

Subtraction Arithmetic InstructionsSUB

Subtractbyteor wordSBB

Subtractbyteor word with borrowDEC

Decrementbyteor word by1NEG

Negatebyteor wordDAS

Decimaladjustfor subtractionAAS

ASCII adjustfor subtractionCMP

Compareoperands

Mult. And Div. Arithmetic InstructionsMUL

Multiplybyteor word, unsignedDIV

Integerdividebyteor word, unsignedIMUL

Multiplybyteor word, signedIDlV

Integerdividebyteor word, signedAAM

ASCII adjustfor multiplyAAD

ASCII adjustfor divisionCBW

Convertbyteto wordCWD

Convertwordto doubleword

Logic InstructionsANO

"AND" byteor wordOR

Inclusive"OR" byteor wordXOR

Exclusive"OR" byteor wordNOT

Complementationor negationof byteor wordCMP

Compareword or byte

Shift and Rotate InstructionsSAL/SHL Shiftarithmetic/logicalleftbyteor wordSHR

Shift logicalrightbyteor wordSAR

Shiftarithmeticrightbyteor wordROL

Rotateleftbyteor wordROR

Rotaterightbyteor wordRCL

Rotateleftthroughcarry,byteor wordRCR

Rotaterightthroughcarry,byteor word

Flag ControllnstructionsLAHF

LoadAH registerfromflagsSAHF

StoreAH registerin flagsCLC

Clearcarryflag (CF)STC

Setcarryflag (CF)CMC

Complementcarryflag (CF)CL!

Clearinterruptenableflag (IF)STI

Set interruptenableflag (IF)

Figure A4.1 8088/8086 instruction set groupings.

170

Jump InstructionsJMP

Jump to short, nearor far addressJCC

Jump conditional(cc) to shortaddress

Subroutine-Handling/Stack instructionsCALL

Cal!procedureRET

Returnfrom procedurePUSH

Pop word ontostackPOP

Pop word off of stackPUSHF

Push flags ontostackPOPF

Pop flags off of stack

String InstructionsMOVS

Move byteor word stringMOVSB

Move bytestringMOVWS

Moveword stringCMPS

Comparebyteor word stringSCAS

Scan byteor word stringLOOS

Load byteor word stringSTOS

Store byteor word string

Pretixes and Auto-Indexing Instr. tor String OperationsREP

RepeatREPE/REPZ

Repeatwhilenot equal/zeroREPNE/REPNZ Repeatwhile notequal/notzeroCLD

Cleardirectionflag (DF)STO

Set directionflag (DF)

Loop InstructionsLOOP

LoopLOOPE/LOOPZ

Loop if equal/zeroLOOPE/LOOPZ

Loop if not equal/notzero

Input/Output InstructionsIN

Inputbyteor word from l/O spaceOUT

Outputbyteor word to l/O space

Interrupt InstructionsCL!

Clearinterruptenableflag (El)STI

Set interruptenableflag (El)INTn

SoftwareinterruptIRET

InterruptreturnINTO

Interrupt if overflowHLT

Haltuntil interruptor resetWAIT

Wait for TEST pin active

External Synchronization/No operationESC

Escapeto externalprocessorLOCK

Lock bus duringnextinstructionNOP

No operation

MnemonicMeaningFormatOperation Flags Affected

AOO

Addition AOO O, S(S) + (O) ->(O)OF. SF, ZF,AF, PF, CFCarry ->(CF)AOC

Add with carryAOC O, S(S) + (O) +(CF) ->(O)OF. SF. ZF,AF, PF, CF, Carry ->(CF)INC

Inerement by 1INC O(O) + 1 -> (O) OF. SF. ZF,AF, PF

AAA

ASCII adjust forAAA AF. CFaddition

OF. SF, ZF, PF undefined

OAA

Decimal adjust forOAA SF. ZF,AF, PF, CF,addition

OF, undefined

(a)

DestinationSource

Register

RegisterRegister

MemoryMemory

RegisterRegister

Immediate

Memory

ImmediateAeeumulator

Immediate

Destination

Reg16Reg8Memory

(b) (e)

Figure A4.2 (a) Addition instructions. (b) Allowed operands for ADD and ADC instructions. (e) Allowedoperands for INC instruction.

MnemonicMeaningFormatOperation Flags Affected

SUB

SubtraetSUB O,S(O) - (S) ->(O)OF, SF, ZF.AF. PF, CFBorrow -> (CF)SBB

Subtraet with borrowSBB O,S(O) - (S) - (CF) ->(O)OF. SF. ZF,AF, PF, CF

OEC

Oeerementby 1OEC O(O) - 1 -> (O) OF. SF. ZF,AF. PF

NEG

Negate NEG OO- (O) ->(O) OF, SF, ZF,AF, PF, CF1 -> (CF)DAS

Decimal adjust forDAS SF, ZF,AF, PF, CF,subtraetion

OF undefined

AAS

ASCII adjust forAAS AF, CFsubtraetion

OF, SF, ZF.PF undefined

(a)

DestinationSource

Register

RegisterRegister

MemoryMemory

RegisterAeeumulator

Immediate

Register

Immediate

Memory

Immediate

Destination

Reg16Reg8Memory

Destination

RegisterMemory

(b) (e) (d)

Figure A4.3 (a) Subtraction instructions. (b) Allowed operands for SUB and SBB instructions. (e) Allowedoperands for NEG instruction.

171

Mnemonic MeaningFormal

.

Operalion Flags Affecled

MUL

Multiply MULS(AL) . (S8) -->(AX)OF, CF(unsigned)

(AX) . (S16) -->(DX),(AX)SF, ZF,AF, PF undefinedDIV

Division DIV S(1) Q((AX)/(S8)) -->(AL)OF, SF, ZF,AF, PF, CF(unsigned)

R((AX)/(S8)) -->(AH)undefined

(2) Q((DX,AX)/(S16))--> (AX) R((DX,AX)/(S16)) -->(DX)If Q is FF16in case (1) orFFFF16in case (2), thenIype O interrupl occursIMULInteger multiplyIMULS(AL) . (S8) -. (AX)OF, CF

(signed)(AX) . (S16) -->(DX),(AX)SF, ZF,AF, PF undefined

IDIVInteger divideIDIV S(1) Q((AX)/(S8)) -->(AL)OF, SF, ZF,AF, PF, CF

(signed)R((AX)/(S8)) -->(AH)undefined

(2) Q((DX,AX)/(S16)) -->(AX) R((DX,AX)/(S16)) -->(DX)If Q is positive and exceeds7FFF16or if Q is negativeand becomes less than800116,then type O interruptoccursAAM

Adjust AL forAAMQ((AL)/10) -->(AH)SF, ZF, PFmultiplication

R((AU10) -->(AL)OF, AF, CF undefinedAAD

Adjust AX forAAD(AH) . 10 + (AL) -->(AL)SF, ZF, PFdivision

00 -->(AH)OF, AF, CF undefinedCBW

Convert bytetoCBW(MSB of AL) -->(Al! bits of AH)Noneword CWD

Convert word toCWD(MSB of AX) -->(Al! bits of DX)Nonedouble word

(a)

Source

Reg8Reg16Mem8Mem16

(b)

Figure A4.4 (a) Multiplication and division arithmetic instructions. (b) Allowed operands.

Mnemonic MeaningFormat "1Operation Flags Affected

ANO

logieal ANOANO O,S(S) (O) ----.(O)OF, SF, ZF, PF, CFAF undefinedOR

logieallnelusive-OROR O,S(S) + (O) ----.(O)OF, SF, ZF, PF, CFAF undefinedXOR

logieal Exelusive-ORXOR O,S(S) EB (O) ----.(O)OF, SF, ZF,PF, CFAF undefinedNOT

logieal NOTNOTO(O) ----.(O) None

(a)

DestinationSource

Register

RegisterRegister

MemoryMemory

RegisterRegister

Immediate

Memory

ImmediateAeeumulator

Immediate

(b)

Destination

RegisterMemory

(e)

Figure A4.5 (a) Logic instructions. (b) Allowed operands for the AND, OR, and XOR instructions. (e) Allowedoperands for NOT instruction.

Mnemonic MeaningFormatOperation Flags Affected

SAUSHl

Shift arithmetieSAUSHl O,CountShift the (O) left by the numberCF, PF, SF, ZFleft/shift

of bit positions equal to CountAF undefinedlogiealleft

and fill the vaeatedbits positionsOF undefined if eount ~ 1on the right with zerosSHR

Shift logiealSHR O,CountShift the (O) right by the numberCF, PF, SF, ZFright

of bit positions equal to CountAF undefined

and fill the vaeated bit positionsOF undefined if eount ~ 1

on the left with zerosSAR

Shift arithmetieSAR O, CountShift the (O) right by the numberSF, ZF, PF, CFright

of bit positions equal to CountAF undefinedand fill the vaeated bit positions

OF undefined if eount ~ 1on the left with the original most signifieant bit

(a)

DestinationCount

Register

1Register

Cl

Memory

1Memory

Cl

(b)

Figure A4.6 (a) Shift instructions. (b) Allowed operands.

MnemonicMeaningFormal

!Operalion Flags Affecled

ROL

Rolate leftROL O,CountRolale the (O) left by Ihe number of bitCF

positions equal to Count. Each bit

OF undefined

shifted out from the leftmost bit goes

if count of. 1

back into the rightmost bit position.RORRotate rightROR O,CountRotate the (O) right by the number of bitCF

positions equal to Count. Each bit shifted

OF undefined

out from the rightmost bit goes into

if count of. 1

the leftmost bit position.RCl

Rotate leftRClO,CountSame as ROL except carry is attachedtoCF

through carry

(O) for rotation.OF undefined

if count of. 1RCRRotate rightRCR O,CountSame as ROR except carry is attachedtoCF

through carry

(O) for rotation.OF undefined

if count of. 1

(a)

DeslinalionCounl

Register

1

Register

Cl

Memory

1

Memory

Cl

(b)

Figure A4.7 (a) Rotate instructions. (b) Allowed operands.

MnemonicMeaning OperalionFlags Affecled

lAHF

load AH from flags(AH) +- (Flags)None

SAHF

Store AH into flags(Flags)+-(AH)SF, ZF,AF, PF, CF

ClC

Clear carry flag(CF) +- OCF

STC

Set carry flag(CF) +-1CF

CMC

Complement carry flag(CF)+- (CF)CF

CL!

Clear interrupt flag(IF)+- OIF

STI

Set interruptflag(IF) +-1IF

AH

7

(a)

SF =SignflagZF =ZeroflagAF =AuxiliaryPF =ParityflagCF =Carry flag- =Undefined(donotuse)

(b)

o

Figure A4.8 (a) Flag-control instructions. (b) Format o, the AH register lor the lAHF and SAHF instructions.

174

Mnemonic Meaning

FormatOperation Flags Affected

CMP

CompareCMP D,S(O) - (S) is used in settingCF, AF, OF, PF, SF, ZFor resetting the flags

(a)

DestinationSource

Register

RegisterRegister

MemoryMemory

RegisterRegister

Immediate

Memory

ImmediateAccumulator

Immediate

(b)

Figure A4.9 (a) Compare instruction. (b) Allowed operands.

MnemonicMeaningFormatOperation Flags Affected

JMP

UnconditionalJMP OperandJump is initiatedto theNonejump

address specified by theoperand

(a)

Operands

Short-labelNear-IabelFar-Iabel

Memptr16Regptr16Memptr32

(b)

Figure A4.10 (a) Unconditional jump instruction. (b) Allowed operands.

Mnemonic

MeaningFormatOperation Flags Affected

Jcc

ConditionalJcc OperandIf the specified condition ccNone

jump

is true the jump to theaddress specified by theoperand is initiated;otherwise the nextinstruction is executed.

(a)

MnemonicMeaning Condition

JA

Above CF = Oand ZF = O

JAE

Above or equalCF = O

JB

Below CF = 1

JBE

Below or equalCF = 1 or ZF = 1

JC

Carry CF = 1

JCXZ

CX register is zero(CF or ZF) = O

JE

Equal ZF = 1

JG

Greater ZF = O and SF = OF

JGE

Greateror equalSF = OF

JL

Less (SF xor OF) = 1

JLE

Less or equal((SF xor OF) or ZF) = 1

JNA

Not above CF= 1 or ZF = 1

JNAE

Not above nor equalCF= 1

JNB

Not below CF = O

JNBE

Not below nor equalCF = Oand ZF = O

JNC

Not carry CF = O

JNE

Not equal ZF = O

JNG

Not greater ((SF xor OF) or ZF) = 1

JNGE

Not greater nor equal(SF xor OF) = 1

JNL

Not less SF = OF

JNLE

Not less nor equalZF = O and SF = OF

JNO

Not overflowOF = O

JNP

Not parity PF = O

JNS

Not sign SF = O

JNZ

Not zero ZF=O

JO

Overflow OF = 1

JP

Parity PF= 1

JPE

Parity even PF = 1

JPO

Parity odd PF = O

JS

Sign SF = 1

JZ

Zero ZF = 1

(b)

Figure A4.11 (a) Conditional jump instruction. (b) Types 01conditional jump instructions.

176

,Mnemonic Meaning

FormatOperation Flags Affected

CALL

Subroutine cal!CALL operandExecution continues fromNone

the address of the subroutine specified by the operandoInformation required to returnback to the main programsuch as IP and CS are savedon the stack.

(a)

Operand

Near-procFar-procMemptr16Regptr16Memptr32

(b)

Figure A4.12 (a) Subroutine call instruclion. (b) Allowed operands.

MnemonicMeaningFormal Operation Flags Affected

RET

ReturnRET or RET OperandReturn lo the main programNone

by restoring IP (and CS for far-proc). If Operand is present,it is added to the contents of SP.

(a)

Operand--None

Disp16

(b)

Figure A4.13 (a) Return instruction. (b) Allowed operands.

Mnemonic Meaning FormatOperation Flags Affected

PUSH

Push word onto stackPUSH S((SP))

MnemonicMeaningFormatOpilration Flags Affected

MOVS

Move stringMOVSB/MOVSW((ES)O + (01));-((OS)O +(SI))None(SI);- (SI) 1 or 2 (DI) ;- (DI) 1 or 2CMPS

Compare stringCMPSB/CMPSWSet flags as per CF, PF, AF, ZF,SF, OF

((OS)O + (St)) - ((ES)O +(DI)) (SI);- (SI) 1 or 2(DI) ;- (DI) 1 or 2SCAS

Sean stringSCASB/SCASWSet flags as per CF, PF, AF, ZF,SF, OF

(AL or AX) - ((ES)O + (DI)) (01);-(DI) 1 or 2LOOS

Load stringLOOSB/LOOSW(AL or AX);- ((OS)O +(SI))None

(SI);- (SI) 1 or 2STOS

Store stringSTOSB/STOSW((ES)O + (01));-(AL or AX) 1 or 2None(01);-(DI) 1 or 2

Figure A4.17 Basic string instructions

PrefixUsed withMeaning

REP

MOVSRepeatwhile not end of stringSTOS

CX*O

REPE/REPZ

CMPSRepeatwhile not end of stringSCAS

and strings are equalCX * O and ZF = 1

REPNE/REPNZ

CMPSRepeat while not end of stringSCAS

and strings are not equalCX * O and ZF = O

Figure A4.18 Prefixes for use with the basic string operations.

MnemonicMeaningFormatOperationFlags Affected

CLO

Clear OFCLO(OF);-OOF

STO

Set DFSTO(OF);-1OF

Figure A4.19 Instructions for selecting autoincrementing and

autodecrementingin string instructions.

MnemonicMeaning Format"Operation

IN

Input direct IN Acc,Port(Acc) +-(Port)ACC =AL or AX

Input indirect (variable)

IN Acc,DX(Acc) +- ((DX))

OUT

Output direct OUT Port,Acc(Port) +-(Acc)

Output indirect (variable)

OUT DX,Acc((DX)) +-(Acc)

Figure A4.20 Input/output instructions.

MnemonicMeaning FormatOperation Flags Affected

CL!

Clear interrupt flagCL!0-+ (IF) IF

STI

Set interruptflagSTI1 -+ (IF) IF

INT n

Type n software interruptINT n(Flags) -+ ((SP) - 2)TF,IF0-+ TF,IF (CS) -+ ((SP) - 4)(2 +4 . n) -+ (CS)(IP) -+ ((SP) - 6)(4 . n) -+ (IP)IRET

Interrupt return IRET((SP)) -+ (IP) Al!

((SP) +2) -+ (CS) ((SP) +4) -+ (Flags)(SP) +6 -+ (SP)INTO

Interrupt on overflowINTOINT 4 steps TF,IF

HLT

Halt HLTWait for an externalNone

interrupt or reset to occurWAIT

Wait WAITWait for TEST input toNone

go active

Figure A4.21 Interrupt instructions.