Direct addressing in assembly language involves using a name to refer to a memory location, which is then translated into an assignment operation during program execution. Here’s how this process unfolds:
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Definition and Usage: When a variable or label (e.g., number dw 1234) is defined, it is assigned a specific memory address by the assembler.
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Compilation Phase: The assembler translates high-level constructs into machine code. For example, the instruction mov ax, number directs the CPU to load the value stored at the memory location associated with number.
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Execution Phase: During runtime, the CPU uses the computed address (e.g., 0x0000FFFF) to access the memory location and retrieve or modify data.
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Comparison with High-Level Languages: While higher-level languages abstract this process, understanding direct addressing in assembly provides insight into how variables are managed at a low level, enhancing one’s grasp of computer architecture and programming concepts.
This mechanism allows for efficient and flexible data manipulation, aligning the explicit nature of assembly language with the fundamental operations of a computer system.