Dr Vinita Kumari

8086 instructions

Arithmetic Instructions

ADD and ADC

Source may be an immediate number, a register

or a memory location specified by any one of the

24 addressing modes

The destination may be a register or memory

location

Source and destination both can not be memory

location

Note: For 8085, DCR instruction, used for both

register and memory. e.g DCR B, DCR M

Example:

NEG AL

NEG BX

NEG BYTE PTR [BX]-Replace byte at offset [BX] in DS with its 2’s complement

NEG WORD PTR [BP]- Replace word at offset [BP] in SS with its 2’s complement

CMP AL,01-

CMP BH, CL

CMP CX, TEMP_MIN- compare with word in CX with word in DS

CMP TEMP_MIN, CX

CMP PRICES[BX], 49H- Compare immediate 49H with byte at offset [BX] in array PRICES

MUL

MUL source

Multiplies an unsigned byte from source times an

unsigned byte in AL register or unsigned word in

AX register

Example

MUL BH- AL times BH, result in AX

MUL CX- AX times CX, result high word in DX,

low word in AX

MUL BYTE PTR [BX]- AL times byte in DS

pointed by [BX]

Logical Instructions

JA

JAE