Difference between Implied addressing mode and Immediate addressing mode
Prerequisite – Addressing Modes
1. Implied Addressing Mode :
In implied addressing mode, the operands are specified implicitly in the definition of the instruction. All the instructions which reference registers that use an accumulator are implied mode instructions. Zero address instructions in a stack organised computer are also implied mode instructions. Thus, it is also known as stack addressing mode.
2. Immediate Addressing Mode :
In Immediate addressing mode, the operand is specified in the instruction itself.In this mode, the operand field contains the actual operand to be used in conjunction with the operation specified in the instruction.
Difference between Implied Addressing Mode and Immediate Addressing Mode :
S.No. | Implied Addressing Mode | Immediate Addressing Mode |
---|---|---|
1. | In Implied addressing mode, no operand is specified in the instruction . | In Immediate addressing mode, operand is specified in the instruction itself . |
2. | Basically, the operands are specified implicitly in the definition of instruction . | Here, the operands are contained in an operand field rather than address field . |
3. | This type of mode can be used in all register reference instructions . | This type of mode is quite useful for initializing the registers to a constant value . |
4. | It requires 8 bits or 16 bits long data and is the part of instruction. | It requires more bits than the address. |
5. | There is no need to acquire a operand . | It is fast in acquiring an operand . |
6. | Zero-address instructions in a stack-organized computer are implied-mode instructions . | The address field of an instruction may specify either a memory word or a processor register. |
7. | Example: CMA (Complement Accumulator) | Example: MVI A 45 |
Feature | Implied Addressing | Immediate Addressing |
Addressing method | Implicit: the operand’s location is determined by the instruction opcode | Explicit: the operand value is directly specified in the instruction |
Operand size | Typically 8-bit or 16-bit | Typically 8-bit or 16-bit, but can also be 32-bit |
Flexibility | Less flexible: only works with predefined memory locations or registers | Less flexible: only allows for immediate values as operands |
Code size | Requires less code: operand location is determined by the instruction opcode, which is shorter | Requires more code: additional instructions are needed to load the immediate operand into a register |
Execution speed | Faster: operand location is determined directly from the instruction opcode | Slower: additional instructions are needed to load the immediate operand into a register |
Memory usage | Does not use additional memory | Uses additional memory to store immediate values |
Complexity | Less complex: requires fewer instructions and is generally easier to use and debug | More complex: requires additional instructions and memory accesses, and can be more difficult to debug |