Adressierungsmethoden

Adressierungsmethoden, also known as addressing modes, are the techniques used by computer processors to specify operands for instructions. These methods determine how the processor interprets the address part of an instruction to locate the data it needs to operate on. Different addressing modes offer varying levels of flexibility and efficiency for accessing memory.

Immediate addressing is the simplest mode, where the operand is directly included within the instruction itself. For example, an instruction might be "ADD 5," meaning add the value 5 to the accumulator.

Register addressing uses a register within the CPU to hold the operand. Instructions like "ADD R1" would add the contents of register R1 to the accumulator. This is very fast as register access is much quicker than memory access.

Direct addressing involves specifying the exact memory address of the operand in the instruction. An instruction like "LOAD 1000" would fetch data from memory location 1000. This offers direct access but requires a larger address field in the instruction.

Indirect addressing uses a memory address that contains the address of the operand. The processor first reads the address from the specified memory location, and then uses that address to access the actual data. This allows for dynamic addressing and larger address spaces.

Register indirect addressing is similar to indirect addressing but uses a register to hold the address of the operand. This combines the speed of register access with the flexibility of indirect addressing.

Indexed addressing uses a register (the index register) to hold an offset that is added to a base address specified in the instruction. This is useful for accessing elements within arrays or tables, as the base address remains constant while the index register is incremented.

Implied or inherent addressing means the operand is implicitly defined by the instruction itself. For example, the increment instruction often implicitly operates on the accumulator.

These addressing modes allow programmers and compilers to choose the most efficient way to access data based on the specific needs of an operation.