The document discusses the different addressing modes of the 8086 processor. There are 7 addressing modes: immediate, implicit, direct, register, register indirect, based indexed, and register relative. Each mode describes how an instruction specifies the location of operands. For example, immediate mode provides the data in the instruction itself, while register indirect uses a register containing the address of the data.

1. Addressing Modes of 8086
Immediate - The data is provided in the instruction.
Eg.
1. MOV BL, 26H ;Copies 8-bit data 26H into BL register
2. MOV CX, 4567H ;Copies 16-bit data 4567H into CX register pair
Implicit - Such Instruction does not have any Operand.
Eg.
1. STC ;sets the carry flag to one
Direct - The instruction operand specifies the memory address (offset) where data is
located.
Eg.
1. MOV CL, [9823H] ;9823H is the effective address [EA] directly written in the
instruction
Register - References the data is in a register or in a register pair.
Eg.
1. MOV BX, CX ;Copies the 16-bit contents of CX into BX
2. MOV CL, BL ; Copies 8-bit contents of BL into CL.
Register Indirect - Instruction specifies a register containing an address, where data is
located. This addressing mode works with SI, DI, BX and BP registers.
Eg. GIVEN INFO: [DI]=0030H, DS=7205H
1. MOV [DI], BX ;Here, Effective Address (EA)=[DI]
;Physical Address (PA)=10H*DS+EA72050H+0030H=72080H
;Contents of BX pair is copied to 72080H & 72081H resp.
Based Indexed - The contents of a base register (BX or BP) is added to the contents of an
index register (SI or DI), the resulting value is a pointer to location where data resides.
Eg. GIVEN INFO: [AX] =1000H, [BX] =1530H, TOT=08H (displacement), [SI] =1000H,
DS=4000H
1. MOV AX, [BX] [SI] ; EA=[BX]+[SI] = 1530H+1000H  EA=2530H
;PA=10H*DS+EA = 40000H+2530H=42530H
2. MOV TOT [SI] [BX], CL ; EA=[BX]+[SI]+offset = 1530H + 1000H + 0008H
; PA=10H*DS+EA40000H+2583H=42538H
J.G. Shewaramani
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2. Addressing Modes of 8086
Register Relative– 8-bit or 16-bit displacement is added with contents of any one of BX,
BP, SI, DI
Eg. GIVEN INFO: [BX] =1000H, DS=4000H
1. MOV AX, 50H [BX] ; EA = [BX]+50H = 1050H
; PA= 10H*DS+EA40000H+1050H=41050H
Relative Based Indexed - 8-bit or 16-bit instruction operand is added to the contents of a
base register (BX or BP) and index register (SI or DI); the resulting value is a pointer to
location where data resides.
Eg. GIVEN INFO: [BX] =2000H, [SI] =1000H, DS=4000H
1. MOV AX, 5000[BX] [SI] ;EA=[BX]+[SI]+displacement2000H+1000H+5000H
;PA=10H*DS+EA = 40000H+8000H=48000H
J.G. Shewaramani
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