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WalesComputer ScienceQuick questions
Unit 4 Computer Architecture, Data, Communication and Applications
Quick questions on Programs and program construction: assembly language, instruction sets and addressing modes - WJEC A-Level Computer Science
4short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is the structure of an instruction?Show answer
Knowing this split is the key to reading any low-level instruction: first what to do (opcode), then what to do it to (operand, as interpreted by the addressing mode).
What are addressing modes?Show answer
Addressing modes decide how the operand is interpreted. In immediate addressing the operand is the actual value to use. In direct addressing the operand is the memory address holding the value. In indirect addressing the operand is the address of a location that itself holds the address of the data.
What is q1?Show answer
State the role of the opcode in a machine instruction. [1 mark]
What is q2?Show answer
In direct addressing, what does the operand contain? [1 mark]
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