Addressing Modes

Key Instructions in the 8086 Instruction Set

The addressing modes of computer architecture are the various ways in which operand(s) of an instruction are specified. These modes define how the processor finds the data it needs to execute a command. The Intel 8086 microprocessor has support for many addressing modes, each granting flexibility in addressing memory and registers at the same time.

Below are the main addressing modes supported by the 8086

Immediate Addressing

In case of immediate addressing, the operand is a constant value or immediate data that is part of the instruction itself.
Example: MOV AX, 1234h – copies value 1234h into AX.

Register Addressing

In register addressing, the operand is placed in one of the CPU registers.
Example: MOV AX, BX – moves the contents of register BX into register AX.

Direct Addressing

In direct addressing, the operand’s address is directly specified in the instruction itself.
Example: MOV AX, [1234h] – displaces register AX with the data stored at the memory location 1234h.

Indirect Addressing

In indirect addressing, the address of the operand is stored in a register or memory location, and the data is at that address.
Example: MOV AX, [BX] – copies the data pointed to by a 16-bit signed offset relative to a 16-bit register with data type of pointer into a 16-bit register with data type of integer.

Indexed Addressing

In indexed addressing, the operand’s address is obtained by computing the offset together with a base address stored in a register.
Example: MOV AX, [BX+SI] – Moves the data located at the address formed by adding the contents of BX and SI registers into register AX.

Based Addressing

Like indexed addressing, but the base address is added to the offset in the instruction.
Example: MOV AX, [1234h+SI] – loads register AX with data from the address that is 1234h added with SI.

Based Indexed Addressing

Combines based and listed addressing modes, in which an offset is introduced to a base deal with stored in a sign in, and an index sign in is used to in addition regulate the address.
Example: MOV AX, [BX DI 10h] – movements the facts positioned on the cope with shaped through adding the contents of BX, DI, and an instantaneous offset of 10h into sign up AX.

8086 Instruction Set

The 8086 instruction set is key to understanding the Intel 80 coding pattern and its significant significance as a path-making chip among x patterns. Unveiled in 1978, it brought innovation into computing by having the ability to provide better overall performance and memory attributes than earlier devices. This article investigates the details behind the 8086 instruction set as well its additives of it in matters of class, addressing modes key command and assembly language programming extensions complexes regarding challenges and further advantages.

Table of Content

8086 Instruction Set
Classification of Instructions set
Addressing Modes
Key Instructions in the 8086 Instruction Set
Assembly Language Programming with the 8086
8086 Instruction Set Extensions
FAQs on 8086 Instruction Set