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Difference between Implied addressing mode and Immediate addressing mode

Last Updated : 05 May, 2023
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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
 

 


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