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8086 Addressing Modes Cheat Sheet
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8086 Addressing Modes Cheat Sheet
8086 Addressing Modes Cheat Sheet
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1
Question
What is Addressing Mode?
Answer
Way to tell where processor finds operand for an instruction
2
Question
Which instruction demonstrates immediate addressing in 8086?
Answer
MOV AX, 5
3
Question
What does MOV AX, Data demonstrate?
Answer
Immediate value moved into AX
4
Question
What does register addressing involve?
Answer
Using data already in a register (e.g., MOV BX, AX)
5
Question
In 8086, what does the Effective Address EA represent?
Answer
The address calculated to access the operand
6
Question
What does EA stand for in addressing modes?
Answer
Effective Address
7
Question
What is the format of an immediate addressing example?
Answer
MOV AX, 5 (5 is immediate data)
8
Question
What is the default segment for data operations in 8086?
Answer
DS (Data Segment)
9
Question
What does MOV AX, [1234H] illustrate?
Answer
Direct memory addressing with a fixed address
10
Question
What information does [1234H] provide?
Answer
Memory location 1234H as operand source/destination
11
Question
What does MOV AX, [BX] illustrate?
Answer
Register indirect addressing using BX as pointer
12
Question
In 8086, which segment does BX use by default for memory operands?
Answer
DS (Data Segment)
13
Question
What is the meaning of indirect addressing with [BX]?
Answer
Address is in BX; data retrieved from the memory location BX points to
14
Question
What is indexed addressing in 8086?
Answer
Using a base register plus displacement as the effective address (e.g., [SI+6])
15
Question
How is the effective address calculated in indexed addressing with SI+6?
Answer
EA = SI + 6
16
Question
What does BASED addressing refer to?
Answer
Using a base register with displacement (e.g., [BX+2])
17
Question
In BASED addressing, which base register is commonly used?
Answer
BX (and sometimes BP)
18
Question
What is BASE + INDEXED addressing?
Answer
EA = (Base) + (Index) (e.g., [BX+SI])
19
Question
Give an example of BASE + INDEXED addressing.
Answer
MOV AX, [BX+SI]
20
Question
What does the expression [BX+SI+5] represent?
Answer
Base + Index + Displacement addressing
21
Question
What is the meaning of the INDEXED mode in 8086?
Answer
Using index register with displacement for addressing
22
Question
What does DS (SI) displacement mean in the table?
Answer
Data segment with index register SI and a displacement
23
Question
What does the STRING addressing mode apply to in 8086?
Answer
String operations like MOVSB with source and destination pointers
24
Question
What does MOVSB do in 8086?
Answer
Moves a byte from DS:SI to ES:DI and increments pointers
25
Question
What is the purpose of the implied addressing mode?
Answer
Operands are not specified; implied by instruction (e.g., STC)
26
Question
What does the I/O Direct addressing mode access?
Answer
Direct port address provided (e.g., IN AL, 80H)
27
Question
What does I/O Indirect addressing mode access?
Answer
Port address specified in a register (e.g., IN AL, DX)
28
Question
What is the meaning of EB/EA with 80H in I/O Direct mode?
Answer
Read from I/O port 80H using direct port address
29
Question
What is the relationship between segment and offset in 8086 memory addressing?
Answer
Physical = Segment × 16 + EA
30
Question
What is the ‘EA formula’ in memory addressing?
Answer
EA = Base + Index + Displacement