This document discusses addressing modes used by the Intel 8085 microprocessor. It describes five addressing modes: direct, register, register indirect, immediate, and implicit. For each mode it provides an example instruction showing how the operand address is specified. The document also categorizes the instruction set of the 8085 into groups for data transfer, arithmetic/logical operations, branch control, and I/O and machine control. It provides details on the instructions in each group and defines the stack used by the 8085.

1. Addressing Modes
• The method by which the address of source of
data or the address of destination of result is
given in the instruction is called Addressing
Modes.
• The term addressing mode refers to the way in
which the operand of the instruction is
specified.

2. Types of Addressing Modes
• Intel 8085 uses the following
• addressing modes:
– Direct Addressing Mode
– Register Addressing Mode
– Register Indirect Addressing Mode
– Immediate Addressing Mode
– Implicit Addressing Mode

3. Direct Addressing Mode
• In this mode, the address of the operand is
given in the instruction itself.
LDA 2500H Means that load A from 2500h Memory
location
– LDA is the operation.
– 2500 H is the address of source.
– Accumulator is the destination.

4. Register Addressing Modes
• In this mode, the operand is in general
purpose register.
MOV A,B Move the contents of register B to
A.
MOV is the operation.
B is the source of data.
A is the destination.

5. Register Indirect Addressing
Mode
• In this mode, the address of operand is specified
by a register pair.
MOV A,M Move data from memory location specified
by H-L pair to accumulator.
• MOV is the operation.
• M is the memory location specified by H-L
register pair.
• A is the destination.

6. Immediate Addressing Mode
• In this mode, the operand is specified within
the instruction itself.
MVI A,05H Move 05 H in accumulator.
• MVI is the operation.
• 05 H is the immediate data (source).
• A is the destination.

7. Implicit Addressing Mode
• If address of source of data as well as address
of destination of result is fixed, then there is
no need to give any operand along with the
instruction.
CMA Complement accumulator.
• CMA is the operation.
• A is the source.
• A is the destination.

8. Instruction Set of 8085

9. 8085 INSTRUCTION SET
• Data Transfer Group
• Arithmetic and Logical Group
• Branch Control Group
• I/O and Machine Control Group

10. Arithmetic and Logical Group
• ADD -16 (8+8)
• SUB -16 (8+8)
• INCREMENT -12 (8+4)
• DECREMENT -12 (8+4)
• DOUBLE ADD -04
• SPECIALS -04 (DAA,CMA,STC,CMC)
• ROTATE -04
LOGICAL

11. LOGICAL
• AND - 08
• OR - 08
• XOR - 08
• CMP - 08
• Arithmetic and logical Immediate
(ANI,ORI,XRI,CPI,ADI,ACI,SUI,SBI) - 08

12. Branch Control Group
• JUMP - 10 (9+1)
• CALL - 09
• RETURN - 09
• RESTART - 08

13. I/O and Machine Control Group -18
• STACK - 10
- PUSH - 04
- POP - 04
-XTHL,SPHL- 02
• I/O - 02
• CONTROL - 04 (EI,DI,NOP,HLT)

14. Stack of 8085
• It is the set of memory locations defined by
programmer in a main program.
• It is used to store the information during
execution of the program
• The stack is a LIFO structure.(Last In First Out.)