Addressing mode

addressing mode

1. ADDRESSING MODE

2. TYPES OF ADDRESSING MODES: IMPLIED MODE IMMEDIATE MODE REGISTER MODE REGISTER INDRECT MODE AUTO-INCREMENT AUTO-DECREMENT DIRECT ADDRESS MODE INDIRECT ADDRESS MODE RELATIVE ADDRESS MODE INDEXED ADDRESSING MODE BASE REGISTER ADDRESSING MODE

3. IMPLIED MODE: In this mode the operands are specified implicitly in the definition of Instruction.   For example, the instruction "complement accumulator" i.e. CMA is an implied- mode instruction because the operand in the accumulator register is implied in the definition of the instruction.

4. IMMEDIATE MODE: In this, operand is directly provided as a constant. Data is constant, No computation required to calculate effective address as data is directly given in instruction. When we use constants in programming, it means immediate mode is involved. Range of operand depends on length of address field.

5. REGISTER MODE: Operand is present in register. Register number is written in instruction. Address field represent the number of register. Size of instruction is small as registers are small in size.

6. REGISTER INDIRECT MODE: Register contains address of operand rather than operand itself. Address of memory is present in register. Memory contains operand.

7. AUTO-INCREMENT MODE: It is Special case of register indirect addressing mode.

8. DIRECT ADDRESS MODE: Actual address is given in the instruction. It is used to access variables. Effective address is directly given in instructions.

9. Indirect addressing mode: Used to implement pointers and passing parameters. Two memory access is required.

10. RELATIVE ADDRESS MODE:

11. INDEXED ADDRESSING MODE: Use to access or implement the array efficiently. Multiple registers required to implement. Any element can be accessed without changing instruction.

12. BASE REGISTER ADDRESSING MODE Used in program relocation.