Learn: Addressing Modes

Welcome!I've reviewed your growth areas and created this lesson to help strengthen your understanding of Addressing Modes. Let's explore this topic step by step!

What are Addressing Modes?Addressing Modes determine how the CPU accesses data stored in memory during program execution. They specify the location of the operand, which is the value the instruction operates on. Understanding addressing modes is important for optimising program instructions and ensuring efficient memory use.

Immediate Addressing ModeIn Immediate Addressing Mode, the actual value of the operand is included directly within the instruction. This is efficient because no memory lookup is required, but it is limited to small values that fit within the instruction size.

Direct Addressing ModeIn Direct Addressing Mode, the instruction specifies the memory address where the operand is stored. The CPU retrieves the value from this address to process. While simple and straightforward, it requires a memory lookup.

Indirect Addressing ModeIn Indirect Addressing Mode, the instruction specifies a memory location that holds the address of the operand. The CPU first retrieves the address from this location and then accesses the operand. This mode is useful for accessing data structures like arrays or linked lists.

Indexed Addressing ModeIndexed Addressing Mode uses an offset value, often stored in an index register, added to a base address to calculate the effective memory address of the operand. This is commonly used for accessing elements in arrays.

Review Time!Great work! You've learned about the main addressing modes: Immediate, Direct, Indirect, and Indexed. Let's test your understanding with a few questions.