1. CS-401 Computer Architecture & Assembly Language Programming
Lecture-7
Addressing Modes

2. In the Last Lecture
We discussed
- Subtraction
- Jump

3. Addressing Modes jnz Jump if the zero flag is not set.
Zero flag is set if the last logical or mathematical instruction has produced a zero in its destination.

4. Addressing Modes
Offset Addressing
mov ax,[num1]

5. Addressing Modes
Register Indirect
mov ax, [bx]

6. Register Indirect + Offset
Addressing Modes
Register Indirect + Offset
mov ax,[bx+num1];base + offset
mov ax,[si+num1];index + offset

7. Addressing Modes
Base + Index
mov ax,[bx+si]

8. Addressing Modes
Base + Index + Offset
mov ax,[bx+si+num1]

9. Addressing Modes mov ax,[num1] ; (o) - Offset mov ax,[bx] ; (b) - Base
mov ax,[si] ; (i) - Index
mov ax,[bx+num1] ; b+o
mov ax,[si+num1] ; i+o
mov ax,[bx+si] ; b+i
mov ax,[bx+si+num1] ; b+i+o

10. Segment Override Prefix
Instruction Opcode
mov ax,[cs:bx] 2E9B07
mov ax,[es:bx] 268B07
mov ax,[ss:bx] 368B07
mov ax,[bx] 8B07