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Gursharan Singh
Maninder Kaur
12-Dec-11
www.eazynotes.com 1
Gursharan Singh
mailme@gursharansingh.in
Maninder Kaur
mailme@maninderkaur.in
www.eazynotes.com
Instruction Set of 8086
? An instruction is a binary pattern designed 
inside a microprocessor to perform a specific 
function.
? The entire group of instructions that a 
microprocessor supports is called 
Instruction Set.
? 8086 has more than 20,000 instructions.
12-Dec-11 2
Gursharan Singh
Maninder Kaur
www.eazynotes.com
Classification of Instruction Set
? Data Transfer Instructions
? Arithmetic Instructions
? Bit Manipulation Instructions
? Program Execution Transfer Instructions
? String Instructions
? Processor Control Instructions
12-Dec-11 3
Gursharan Singh
Maninder Kaur www.eazynotes.com
Data Transfer Instructions
? These instructions are used to transfer data 
from source to destination.
? The operand can be a constant, memory 
location, register or I/O port address.
12-Dec-11 4
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Maninder Kaur
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Data Transfer Instructions
? MOV Des, Src:
? Src operand can be register, memory location or immediate 
operand.
? Des can be register or memory operand.
? Both Src and Des cannot be memory location at the same 
time.
? E.g.:
? MOV CX, 037A H
? MOV AL, BL
? MOV BX, [0301 H]
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Data Transfer Instructions
? PUSH Operand:
? It pushes the operand into top of stack.
? E.g.: PUSH BX
? POP Des:
? It pops the operand from top of stack to Des.
? Des can be a general purpose register, segment register 
(except CS) or memory location.
? E.g.: POP AX
12-Dec-11 6
Gursharan Singh
Maninder Kaur
Page 2


Gursharan Singh
Maninder Kaur
12-Dec-11
www.eazynotes.com 1
Gursharan Singh
mailme@gursharansingh.in
Maninder Kaur
mailme@maninderkaur.in
www.eazynotes.com
Instruction Set of 8086
? An instruction is a binary pattern designed 
inside a microprocessor to perform a specific 
function.
? The entire group of instructions that a 
microprocessor supports is called 
Instruction Set.
? 8086 has more than 20,000 instructions.
12-Dec-11 2
Gursharan Singh
Maninder Kaur
www.eazynotes.com
Classification of Instruction Set
? Data Transfer Instructions
? Arithmetic Instructions
? Bit Manipulation Instructions
? Program Execution Transfer Instructions
? String Instructions
? Processor Control Instructions
12-Dec-11 3
Gursharan Singh
Maninder Kaur www.eazynotes.com
Data Transfer Instructions
? These instructions are used to transfer data 
from source to destination.
? The operand can be a constant, memory 
location, register or I/O port address.
12-Dec-11 4
Gursharan Singh
Maninder Kaur
www.eazynotes.com
Data Transfer Instructions
? MOV Des, Src:
? Src operand can be register, memory location or immediate 
operand.
? Des can be register or memory operand.
? Both Src and Des cannot be memory location at the same 
time.
? E.g.:
? MOV CX, 037A H
? MOV AL, BL
? MOV BX, [0301 H]
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Data Transfer Instructions
? PUSH Operand:
? It pushes the operand into top of stack.
? E.g.: PUSH BX
? POP Des:
? It pops the operand from top of stack to Des.
? Des can be a general purpose register, segment register 
(except CS) or memory location.
? E.g.: POP AX
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Data Transfer Instructions
? XCHG Des, Src:
? This instruction exchanges Src with Des.
? It cannot exchange two memory locations directly.
? E.g.: XCHG DX, AX
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Data Transfer Instructions
? IN Accumulator, Port Address:
? It transfers the operand from specified port to accumulator 
register.
? E.g.: IN AX, 0028 H
? OUT Port Address, Accumulator:
? It transfers the operand from accumulator to specified port.
? E.g.: OUT 0028 H, AX
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Data Transfer Instructions
?LEA  Register, Src:
? It loads a 16-bit register with the offset 
address of the data specified by the Src.
? E.g.: LEA BX, [DI]
? This instruction loads the contents of DI 
(offset) into the BX register.
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Data Transfer Instructions
? LDS Des, Src:
? It loads 32-bit pointer from memory source to 
destination register and DS.
? The offset is placed in the destination register and the 
segment is placed in DS.
? To use this instruction the word at the lower memory 
address must contain the offset and the word at the 
higher address must contain the segment.
? E.g.: LDS BX, [0301 H]
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Data Transfer Instructions
? LES Des, Src:
? It loads 32-bit pointer from memory source to 
destination register and ES.
? The offset is placed in the destination register and the 
segment is placed in ES.
? This instruction is very similar to LDS except that it 
initializes ES instead of DS.
? E.g.: LES BX, [0301 H]
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Data Transfer Instructions
? LAHF:
? It copies the lower byte of flag register to AH.
? SAHF:
? It copies the contents of AH to lower byte of flag register.
? PUSHF:
? Pushes flag register to top of stack.
? POPF:
? Pops the stack top to flag register.
12-Dec-11 12
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Page 3


Gursharan Singh
Maninder Kaur
12-Dec-11
www.eazynotes.com 1
Gursharan Singh
mailme@gursharansingh.in
Maninder Kaur
mailme@maninderkaur.in
www.eazynotes.com
Instruction Set of 8086
? An instruction is a binary pattern designed 
inside a microprocessor to perform a specific 
function.
? The entire group of instructions that a 
microprocessor supports is called 
Instruction Set.
? 8086 has more than 20,000 instructions.
12-Dec-11 2
Gursharan Singh
Maninder Kaur
www.eazynotes.com
Classification of Instruction Set
? Data Transfer Instructions
? Arithmetic Instructions
? Bit Manipulation Instructions
? Program Execution Transfer Instructions
? String Instructions
? Processor Control Instructions
12-Dec-11 3
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Maninder Kaur www.eazynotes.com
Data Transfer Instructions
? These instructions are used to transfer data 
from source to destination.
? The operand can be a constant, memory 
location, register or I/O port address.
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Maninder Kaur
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Data Transfer Instructions
? MOV Des, Src:
? Src operand can be register, memory location or immediate 
operand.
? Des can be register or memory operand.
? Both Src and Des cannot be memory location at the same 
time.
? E.g.:
? MOV CX, 037A H
? MOV AL, BL
? MOV BX, [0301 H]
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Data Transfer Instructions
? PUSH Operand:
? It pushes the operand into top of stack.
? E.g.: PUSH BX
? POP Des:
? It pops the operand from top of stack to Des.
? Des can be a general purpose register, segment register 
(except CS) or memory location.
? E.g.: POP AX
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Data Transfer Instructions
? XCHG Des, Src:
? This instruction exchanges Src with Des.
? It cannot exchange two memory locations directly.
? E.g.: XCHG DX, AX
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Data Transfer Instructions
? IN Accumulator, Port Address:
? It transfers the operand from specified port to accumulator 
register.
? E.g.: IN AX, 0028 H
? OUT Port Address, Accumulator:
? It transfers the operand from accumulator to specified port.
? E.g.: OUT 0028 H, AX
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Data Transfer Instructions
?LEA  Register, Src:
? It loads a 16-bit register with the offset 
address of the data specified by the Src.
? E.g.: LEA BX, [DI]
? This instruction loads the contents of DI 
(offset) into the BX register.
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Data Transfer Instructions
? LDS Des, Src:
? It loads 32-bit pointer from memory source to 
destination register and DS.
? The offset is placed in the destination register and the 
segment is placed in DS.
? To use this instruction the word at the lower memory 
address must contain the offset and the word at the 
higher address must contain the segment.
? E.g.: LDS BX, [0301 H]
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Data Transfer Instructions
? LES Des, Src:
? It loads 32-bit pointer from memory source to 
destination register and ES.
? The offset is placed in the destination register and the 
segment is placed in ES.
? This instruction is very similar to LDS except that it 
initializes ES instead of DS.
? E.g.: LES BX, [0301 H]
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Data Transfer Instructions
? LAHF:
? It copies the lower byte of flag register to AH.
? SAHF:
? It copies the contents of AH to lower byte of flag register.
? PUSHF:
? Pushes flag register to top of stack.
? POPF:
? Pops the stack top to flag register.
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Arithmetic Instructions
? ADD Des, Src:
? It adds a byte to byte or a word to word.
? It effects AF, CF, OF, PF, SF, ZF flags.
? E.g.:
? ADD AL, 74H
? ADD DX, AX
? ADD AX, [BX]
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Arithmetic Instructions
? ADC Des, Src:
? It adds the two operands with CF.
? It effects AF, CF, OF, PF, SF, ZF flags.
? E.g.:
? ADC AL, 74H
? ADC DX, AX
? ADC AX, [BX]
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Arithmetic Instructions
? SUB Des, Src:
? It subtracts a byte from byte or a word from word.
? It effects AF, CF, OF, PF, SF, ZF flags.
? For subtraction, CF acts as borrow flag.
? E.g.:
? SUB AL, 74H
? SUB DX, AX
? SUB AX, [BX]
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Arithmetic Instructions
? SBB Des, Src:
? It subtracts the two operands and also the 
borrow from the result.
? It effects AF, CF, OF, PF, SF, ZF flags.
? E.g.:
? SBB AL, 74H
? SBB DX, AX
? SBB AX, [BX]
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Arithmetic Instructions
? INC Src:
? It increments the byte or word by one.
? The operand can be a register or memory 
location.
? It effects AF, OF, PF, SF, ZF flags.
? CF is not effected.
? E.g.: INC AX
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Arithmetic Instructions
? DEC Src:
? It decrements the byte or word by one.
? The operand can be a register or memory 
location.
? It effects AF, OF, PF, SF, ZF flags.
? CF is not effected.
? E.g.: DEC AX
12-Dec-11 18
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Page 4


Gursharan Singh
Maninder Kaur
12-Dec-11
www.eazynotes.com 1
Gursharan Singh
mailme@gursharansingh.in
Maninder Kaur
mailme@maninderkaur.in
www.eazynotes.com
Instruction Set of 8086
? An instruction is a binary pattern designed 
inside a microprocessor to perform a specific 
function.
? The entire group of instructions that a 
microprocessor supports is called 
Instruction Set.
? 8086 has more than 20,000 instructions.
12-Dec-11 2
Gursharan Singh
Maninder Kaur
www.eazynotes.com
Classification of Instruction Set
? Data Transfer Instructions
? Arithmetic Instructions
? Bit Manipulation Instructions
? Program Execution Transfer Instructions
? String Instructions
? Processor Control Instructions
12-Dec-11 3
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Maninder Kaur www.eazynotes.com
Data Transfer Instructions
? These instructions are used to transfer data 
from source to destination.
? The operand can be a constant, memory 
location, register or I/O port address.
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Maninder Kaur
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Data Transfer Instructions
? MOV Des, Src:
? Src operand can be register, memory location or immediate 
operand.
? Des can be register or memory operand.
? Both Src and Des cannot be memory location at the same 
time.
? E.g.:
? MOV CX, 037A H
? MOV AL, BL
? MOV BX, [0301 H]
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Data Transfer Instructions
? PUSH Operand:
? It pushes the operand into top of stack.
? E.g.: PUSH BX
? POP Des:
? It pops the operand from top of stack to Des.
? Des can be a general purpose register, segment register 
(except CS) or memory location.
? E.g.: POP AX
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Data Transfer Instructions
? XCHG Des, Src:
? This instruction exchanges Src with Des.
? It cannot exchange two memory locations directly.
? E.g.: XCHG DX, AX
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Data Transfer Instructions
? IN Accumulator, Port Address:
? It transfers the operand from specified port to accumulator 
register.
? E.g.: IN AX, 0028 H
? OUT Port Address, Accumulator:
? It transfers the operand from accumulator to specified port.
? E.g.: OUT 0028 H, AX
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Data Transfer Instructions
?LEA  Register, Src:
? It loads a 16-bit register with the offset 
address of the data specified by the Src.
? E.g.: LEA BX, [DI]
? This instruction loads the contents of DI 
(offset) into the BX register.
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Data Transfer Instructions
? LDS Des, Src:
? It loads 32-bit pointer from memory source to 
destination register and DS.
? The offset is placed in the destination register and the 
segment is placed in DS.
? To use this instruction the word at the lower memory 
address must contain the offset and the word at the 
higher address must contain the segment.
? E.g.: LDS BX, [0301 H]
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Data Transfer Instructions
? LES Des, Src:
? It loads 32-bit pointer from memory source to 
destination register and ES.
? The offset is placed in the destination register and the 
segment is placed in ES.
? This instruction is very similar to LDS except that it 
initializes ES instead of DS.
? E.g.: LES BX, [0301 H]
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Data Transfer Instructions
? LAHF:
? It copies the lower byte of flag register to AH.
? SAHF:
? It copies the contents of AH to lower byte of flag register.
? PUSHF:
? Pushes flag register to top of stack.
? POPF:
? Pops the stack top to flag register.
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Arithmetic Instructions
? ADD Des, Src:
? It adds a byte to byte or a word to word.
? It effects AF, CF, OF, PF, SF, ZF flags.
? E.g.:
? ADD AL, 74H
? ADD DX, AX
? ADD AX, [BX]
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Arithmetic Instructions
? ADC Des, Src:
? It adds the two operands with CF.
? It effects AF, CF, OF, PF, SF, ZF flags.
? E.g.:
? ADC AL, 74H
? ADC DX, AX
? ADC AX, [BX]
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Arithmetic Instructions
? SUB Des, Src:
? It subtracts a byte from byte or a word from word.
? It effects AF, CF, OF, PF, SF, ZF flags.
? For subtraction, CF acts as borrow flag.
? E.g.:
? SUB AL, 74H
? SUB DX, AX
? SUB AX, [BX]
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Arithmetic Instructions
? SBB Des, Src:
? It subtracts the two operands and also the 
borrow from the result.
? It effects AF, CF, OF, PF, SF, ZF flags.
? E.g.:
? SBB AL, 74H
? SBB DX, AX
? SBB AX, [BX]
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Arithmetic Instructions
? INC Src:
? It increments the byte or word by one.
? The operand can be a register or memory 
location.
? It effects AF, OF, PF, SF, ZF flags.
? CF is not effected.
? E.g.: INC AX
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Arithmetic Instructions
? DEC Src:
? It decrements the byte or word by one.
? The operand can be a register or memory 
location.
? It effects AF, OF, PF, SF, ZF flags.
? CF is not effected.
? E.g.: DEC AX
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Arithmetic Instructions
? AAA (ASCII Adjust after Addition):
? The data entered from the terminal is in ASCII format.
? In ASCII, 0 – 9 are represented by 30H – 39H.
? This instruction allows us to add the ASCII codes.
? This instruction does not have any operand.
? Other ASCII Instructions:
? AAS (ASCII Adjust after Subtraction)
? AAM (ASCII Adjust after Multiplication)
? AAD (ASCII Adjust Before Division)
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Arithmetic Instructions
? DAA (Decimal Adjust after Addition)
? It is used to make sure that the result of adding two BCD 
numbers is adjusted to be a correct BCD number.
? It only works on AL register.
? DAS (Decimal Adjust after Subtraction)
? It is used to make sure that the result of subtracting two 
BCD numbers is adjusted to be a correct BCD number.
? It only works on AL register.
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Arithmetic Instructions
? NEG Src:
? It creates 2’s complement of a given 
number.
? That means, it changes the sign of a 
number.
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Arithmetic Instructions
? CMP Des, Src:
? It compares two specified bytes or words.
? The Src and Des can be a constant, register or memory 
location.
? Both operands cannot be a memory location at the same 
time.
? The comparison is done simply by internally subtracting 
the source from destination.
? The value of source and destination does not change, but 
the flags are modified to indicate the result.
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Arithmetic Instructions
? MUL Src:
? It is an unsigned multiplication instruction.
? It multiplies two bytes to produce a word or two words to 
produce a double word.
? AX = AL * Src
? DX : AX = AX * Src
? This instruction assumes one of the operand in AL or AX.
? Src can be a register or memory location.
? IMUL Src:
? It is a signed multiplication instruction.
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Arithmetic Instructions
? DIV Src:
? It is an unsigned division instruction.
? It divides word by byte or double word by word.
? The operand is stored in AX, divisor is Src and the 
result is stored as:
? AH = remainder AL = quotient
? IDIV Src:
? It is a signed division instruction.
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Gursharan Singh
mailme@gursharansingh.in
Maninder Kaur
mailme@maninderkaur.in
www.eazynotes.com
Instruction Set of 8086
? An instruction is a binary pattern designed 
inside a microprocessor to perform a specific 
function.
? The entire group of instructions that a 
microprocessor supports is called 
Instruction Set.
? 8086 has more than 20,000 instructions.
12-Dec-11 2
Gursharan Singh
Maninder Kaur
www.eazynotes.com
Classification of Instruction Set
? Data Transfer Instructions
? Arithmetic Instructions
? Bit Manipulation Instructions
? Program Execution Transfer Instructions
? String Instructions
? Processor Control Instructions
12-Dec-11 3
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Data Transfer Instructions
? These instructions are used to transfer data 
from source to destination.
? The operand can be a constant, memory 
location, register or I/O port address.
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Data Transfer Instructions
? MOV Des, Src:
? Src operand can be register, memory location or immediate 
operand.
? Des can be register or memory operand.
? Both Src and Des cannot be memory location at the same 
time.
? E.g.:
? MOV CX, 037A H
? MOV AL, BL
? MOV BX, [0301 H]
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Data Transfer Instructions
? PUSH Operand:
? It pushes the operand into top of stack.
? E.g.: PUSH BX
? POP Des:
? It pops the operand from top of stack to Des.
? Des can be a general purpose register, segment register 
(except CS) or memory location.
? E.g.: POP AX
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Data Transfer Instructions
? XCHG Des, Src:
? This instruction exchanges Src with Des.
? It cannot exchange two memory locations directly.
? E.g.: XCHG DX, AX
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Data Transfer Instructions
? IN Accumulator, Port Address:
? It transfers the operand from specified port to accumulator 
register.
? E.g.: IN AX, 0028 H
? OUT Port Address, Accumulator:
? It transfers the operand from accumulator to specified port.
? E.g.: OUT 0028 H, AX
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Data Transfer Instructions
?LEA  Register, Src:
? It loads a 16-bit register with the offset 
address of the data specified by the Src.
? E.g.: LEA BX, [DI]
? This instruction loads the contents of DI 
(offset) into the BX register.
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Data Transfer Instructions
? LDS Des, Src:
? It loads 32-bit pointer from memory source to 
destination register and DS.
? The offset is placed in the destination register and the 
segment is placed in DS.
? To use this instruction the word at the lower memory 
address must contain the offset and the word at the 
higher address must contain the segment.
? E.g.: LDS BX, [0301 H]
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Data Transfer Instructions
? LES Des, Src:
? It loads 32-bit pointer from memory source to 
destination register and ES.
? The offset is placed in the destination register and the 
segment is placed in ES.
? This instruction is very similar to LDS except that it 
initializes ES instead of DS.
? E.g.: LES BX, [0301 H]
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Data Transfer Instructions
? LAHF:
? It copies the lower byte of flag register to AH.
? SAHF:
? It copies the contents of AH to lower byte of flag register.
? PUSHF:
? Pushes flag register to top of stack.
? POPF:
? Pops the stack top to flag register.
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Arithmetic Instructions
? ADD Des, Src:
? It adds a byte to byte or a word to word.
? It effects AF, CF, OF, PF, SF, ZF flags.
? E.g.:
? ADD AL, 74H
? ADD DX, AX
? ADD AX, [BX]
12-Dec-11 13
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Maninder Kaur www.eazynotes.com
Arithmetic Instructions
? ADC Des, Src:
? It adds the two operands with CF.
? It effects AF, CF, OF, PF, SF, ZF flags.
? E.g.:
? ADC AL, 74H
? ADC DX, AX
? ADC AX, [BX]
12-Dec-11 14
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Arithmetic Instructions
? SUB Des, Src:
? It subtracts a byte from byte or a word from word.
? It effects AF, CF, OF, PF, SF, ZF flags.
? For subtraction, CF acts as borrow flag.
? E.g.:
? SUB AL, 74H
? SUB DX, AX
? SUB AX, [BX]
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Arithmetic Instructions
? SBB Des, Src:
? It subtracts the two operands and also the 
borrow from the result.
? It effects AF, CF, OF, PF, SF, ZF flags.
? E.g.:
? SBB AL, 74H
? SBB DX, AX
? SBB AX, [BX]
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Arithmetic Instructions
? INC Src:
? It increments the byte or word by one.
? The operand can be a register or memory 
location.
? It effects AF, OF, PF, SF, ZF flags.
? CF is not effected.
? E.g.: INC AX
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Arithmetic Instructions
? DEC Src:
? It decrements the byte or word by one.
? The operand can be a register or memory 
location.
? It effects AF, OF, PF, SF, ZF flags.
? CF is not effected.
? E.g.: DEC AX
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Maninder Kaur
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Arithmetic Instructions
? AAA (ASCII Adjust after Addition):
? The data entered from the terminal is in ASCII format.
? In ASCII, 0 – 9 are represented by 30H – 39H.
? This instruction allows us to add the ASCII codes.
? This instruction does not have any operand.
? Other ASCII Instructions:
? AAS (ASCII Adjust after Subtraction)
? AAM (ASCII Adjust after Multiplication)
? AAD (ASCII Adjust Before Division)
12-Dec-11 19
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Arithmetic Instructions
? DAA (Decimal Adjust after Addition)
? It is used to make sure that the result of adding two BCD 
numbers is adjusted to be a correct BCD number.
? It only works on AL register.
? DAS (Decimal Adjust after Subtraction)
? It is used to make sure that the result of subtracting two 
BCD numbers is adjusted to be a correct BCD number.
? It only works on AL register.
12-Dec-11 20
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Maninder Kaur
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Arithmetic Instructions
? NEG Src:
? It creates 2’s complement of a given 
number.
? That means, it changes the sign of a 
number.
12-Dec-11 21
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Maninder Kaur www.eazynotes.com
Arithmetic Instructions
? CMP Des, Src:
? It compares two specified bytes or words.
? The Src and Des can be a constant, register or memory 
location.
? Both operands cannot be a memory location at the same 
time.
? The comparison is done simply by internally subtracting 
the source from destination.
? The value of source and destination does not change, but 
the flags are modified to indicate the result.
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Maninder Kaur
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Arithmetic Instructions
? MUL Src:
? It is an unsigned multiplication instruction.
? It multiplies two bytes to produce a word or two words to 
produce a double word.
? AX = AL * Src
? DX : AX = AX * Src
? This instruction assumes one of the operand in AL or AX.
? Src can be a register or memory location.
? IMUL Src:
? It is a signed multiplication instruction.
12-Dec-11 23
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Arithmetic Instructions
? DIV Src:
? It is an unsigned division instruction.
? It divides word by byte or double word by word.
? The operand is stored in AX, divisor is Src and the 
result is stored as:
? AH = remainder AL = quotient
? IDIV Src:
? It is a signed division instruction.
12-Dec-11 24
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12-Dec-11
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Arithmetic Instructions
? CBW (Convert Byte to Word):
? This instruction converts byte in AL to word in AX.
? The conversion is done by extending the sign bit of AL 
throughout AH.
? CWD (Convert Word to Double Word):
? This instruction converts word in AX to double word in 
DX : AX.
? The conversion is done by extending the sign bit of AX 
throughout DX.
12-Dec-11 25
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Bit Manipulation Instructions
? These instructions are used at the bit level.
? These instructions can be used for:
? Testing a zero bit
? Set or reset a bit
? Shift bits across registers
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Bit Manipulation Instructions
? NOT Src:
? It complements each bit of Src to produce 1’s 
complement of the specified operand.
? The operand can be a register or memory location.
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Maninder Kaur www.eazynotes.com
Bit Manipulation Instructions
? AND Des, Src:
? It performs AND operation of Des and Src.
? Src can be immediate number, register or memory 
location.
? Des can be register or memory location.
? Both operands cannot be memory locations at the same 
time.
? CF and OF become zero after the operation.
? PF, SF and ZF are updated.
12-Dec-11 28
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Maninder Kaur
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Bit Manipulation Instructions
? OR Des, Src:
? It performs OR operation of Des and Src.
? Src can be immediate number, register or memory 
location.
? Des can be register or memory location.
? Both operands cannot be memory locations at the same 
time.
? CF and OF become zero after the operation.
? PF, SF and ZF are updated.
12-Dec-11 29
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Maninder Kaur www.eazynotes.com
Bit Manipulation Instructions
? XOR Des, Src:
? It performs XOR operation of Des and Src.
? Src can be immediate number, register or memory 
location.
? Des can be register or memory location.
? Both operands cannot be memory locations at the same 
time.
? CF and OF become zero after the operation.
? PF, SF and ZF are updated.
12-Dec-11 30
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Maninder Kaur
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FAQs on Instruction Set of 8086

1. What is the instruction set of 8086?
Ans. The instruction set of 8086 refers to the set of commands or operations that the Intel 8086 microprocessor can understand and execute. It includes a wide range of instructions for data manipulation, arithmetic operations, logical operations, branching, and I/O operations.
2. How many instructions are there in the 8086 instruction set?
Ans. The 8086 instruction set consists of over 200 instructions. These instructions are categorized into various groups based on their functionality, such as data transfer, arithmetic, logical, control transfer, string manipulation, and I/O operations.
3. What are the main features of the 8086 instruction set?
Ans. The main features of the 8086 instruction set include: - Support for 16-bit data and 20-bit address bus. - Segmented memory architecture with four segments: code, data, stack, and extra. - Various addressing modes for flexible data access. - Arithmetic and logical operations on binary, decimal, and ASCII data. - Conditional and unconditional branching. - String manipulation instructions for block data transfer and comparison. - Input and output instructions for communication with peripherals.
4. How are instructions executed in the 8086 microprocessor?
Ans. Instructions in the 8086 microprocessor are executed in a sequential manner. The microprocessor reads an instruction from memory, decodes it to determine the operation to be performed, fetches the operands if necessary, performs the operation, and then stores the result back in memory if needed. This process is repeated for each instruction in the program.
5. Can the 8086 instruction set be used in modern computers?
Ans. The 8086 instruction set is quite outdated and not directly compatible with modern computer architectures. However, the x86 instruction set, which is an extension of the 8086 instruction set, is still widely used in modern computers. The x86 instruction set includes backward compatibility with the 8086 instructions and incorporates numerous enhancements and new features to support modern computing needs.
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