先决条件 – 寻址模式
1. 隐式寻址方式：
在隐含寻址模式下，操作数在指令的定义中隐式指定。所有引用寄存器使用累加器的指令都是隐含模式指令。堆栈组织计算机中的零地址指令也是隐含模式指令。因此，它是也称为堆栈寻址模式。
2. 立即寻址模式：
在立即寻址模式下，操作数在指令本身中指定。在这种模式下，操作数字段包含要与指令中指定的操作结合使用的实际操作数。
隐式寻址模式和立即寻址模式的区别：
| 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 |