![Addressing Modes
8086 Microprocessor
1. Direct I/O port Addressing
2. Indirect I/O port Addressing
These addressing modes are used to access data
from standard I/O mapped devices or ports.
In direct port addressing mode, an 8-bit port
address is directly specified in the instruction.
Example: IN AL, [09H]
Operations: PORTaddr
= 09H
(AL) ← (PORT)
Content of port address 09H
is
moved to AL register
In indirect port addressing mode, the instruction
will specify the name of the register which holds
the port address. In 8086, the 16-bit port address
is stored in the DX register.
Example: OUT [DX], AX
Operations: PORTaddr
= (DX)
(PORT) ← (AX)
Content of AX is moved to port
whose address is specified by DX
register.](https://image.slidesharecdn.com/addressingmodes-250126131834-4c9a2fdc/85/Addressing-modes-pdf-for-engineering-student-7-320.jpg)
Addressing modes.pdf for engineering student
- 1. Addressing modes of 8086 1
- 2. Addressing Modes It is the method to specify the operand of an instruction to the microprocessor. The instruction has opcodes that determine what to be done). The operands define the data to be used in the operation. 2
- 3. Types of Addressing modes • Immediate addressing mode • Implicit addressing mode • Direct addressing mode • Register addressing mode • Register Indirect addressing mode • Relative Based Indexed addressing mode • Input/Output addressing mode • String addressing mode 3
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- 7. Addressing Modes 8086 Microprocessor 1. Direct I/O port Addressing 2. Indirect I/O port Addressing These addressing modes are used to access data from standard I/O mapped devices or ports. In direct port addressing mode, an 8-bit port address is directly specified in the instruction. Example: IN AL, [09H] Operations: PORTaddr = 09H (AL) ← (PORT) Content of port address 09H is moved to AL register In indirect port addressing mode, the instruction will specify the name of the register which holds the port address. In 8086, the 16-bit port address is stored in the DX register. Example: OUT [DX], AX Operations: PORTaddr = (DX) (PORT) ← (AX) Content of AX is moved to port whose address is specified by DX register.
- 8. String Addressing mode 8 8086 Microprocessor
- 9. 9 DIVISION in 8086 : 1) When we Divide a word by a byte, word must be in AX register. AL – Quotient , AH – Remainder 2) When Divide a Double word is divided by a word, MSB of the word should be in DX and the LSB should be in AX AX – Quotient , DX – Remainder