When describing assembly instruction words, what does the term mnemonic most precisely represent in the instruction format?
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Aa short abbreviation for the operand address
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Ba short abbreviation for the operation to be performed
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Ca short abbreviation for the data word stored at the operand address
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Dshorthand for machine language
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Ea symbolic label for a memory location
Answer
Correct Answer: a short abbreviation for the operation to be performed
Explanation
Introduction / Context:Assembly language expresses machine instructions using symbolic elements. Disentangling the role of each element (mnemonic, operands, labels, addressing modes) is essential to read or write assembly code with confidence.
Given Data / Assumptions:
- An instruction typically comprises a mnemonic and zero or more operands.
- Operands may be registers, immediate values, or memory references.
- Labels name addresses and are not the mnemonic itself.
Concept / Approach:The mnemonic is the terse keyword naming the operation: for example, MOV, ADD, SUB, JMP. Operands specify sources, destinations, or addresses. The assembler maps the mnemonic plus operands to a specific opcode pattern appropriate for the architecture.
Step-by-Step Solution:Identify the instruction form: MNEMONIC OPERAND(S).Map examples: MOV R0, #5 loads an immediate; ADD R1, R2 adds two registers.Note that the mnemonic names the operation (move, add, jump).Therefore, the definition is a short abbreviation for the operation to be performed.
Verification / Alternative check:Consult any assembler reference; each entry is keyed by mnemonic name and describes the operation semantics and encoding forms for its operands.
Why Other Options Are Wrong:Operand address or data word: these are operand fields, not the mnemonic.
Shorthand for machine language: misleading; mnemonics are symbolic, not the binary itself.
Label: labels are identifiers for addresses and are distinct from mnemonics.
Common Pitfalls:Confusing labels or pseudo-ops (directives) with real instruction mnemonics. Pseudo-ops control the assembler, not the CPU.
Final Answer:a short abbreviation for the operation to be performed