Addressing mode

Addressing mode

• 1.
  ADDRESSING MODE
• 3.
  TYPES OF ADDRESSINGMODES:  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
• 4.
  IMPLIED MODE:  Inthis 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.
• 5.
  IMMEDIATE MODE:  Inthis, 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.
• 6.
  REGISTER MODE:  Operandis 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.
• 7.
  REGISTER INDIRECT MODE: Register contains address of operand rather than operand itself.  Address of memory is present in register.  Memory contains operand.
• 8.
  AUTO-INCREMENT MODE:  Itis Special case of register indirect addressing mode.
• 9.
  DIRECT ADDRESS MODE: Actual address is given in the instruction.  It is used to access variables.  Effective address is directly given in instructions.
• 10.
  Indirect addressing mode: Used to implement pointers and passing parameters.  Two memory access is required.
• 11.
  RELATIVE ADDRESS MODE:
• 13.
  INDEXED ADDRESSING MODE: Use to access or implement the array efficiently.  Multiple registers required to implement.  Any element can be accessed without changing instruction.
• 14.
  BASE REGISTER ADDRESSINGMODE  Used in program relocation.