AQA · GCSE · Computer Science
Course version: 8525 · Version from Sept 2020
Each line of assembly language is assembled into a single machine code…
Full specification wording
Classification of programming languages and translators: each line of assembly language is assembled into a single machine code instruction
Assembly language sits one level above raw binary and uses short mnemonics, such as LDA or ADD, to name operations the processor can carry out.
Checked against the AQA 8525 specification (opens in a new tab) on .
- Point 14 of 19
Study notes
From the checked teaching notes for this specification point.
The idea
Assembly language sits one level above raw binary and uses short mnemonics, such as LDA or ADD, to name operations the processor can carry out. An assembler reads the source file one line at a time and converts each mnemonic line into exactly one machine code instruction, so the relationship between source lines and output instructions is one-to-one rather than one-to-many. This is why assembly is described as a low-level language: the programmer works directly with the instruction set of a particular processor family, and the resulting code is specific to that hardware. A single line may combine an operation with an operand, for example loading a value into a register, but it still maps to one instruction. Contrast this with a high-level language, where one statement such as a loop or a print command may expand into many machine code instructions after translation.
What earns the marks
- An assembler translates assembly language source into machine code.
- Each assembly language line corresponds to exactly one machine code instruction (a one-to-one mapping).
- Assembly uses mnemonics for processor operations and is tied to a specific instruction set or processor family.
- The output is executable machine code made of binary instructions the CPU can run directly.
Common mistakes and how to put them right
Assuming one assembly line can produce several machine code instructions.
Put it right by stressing the strict one-to-one mapping.
Confusing the assembler with a compiler or interpreter.
Put it right: The assembler is the translator specific to assembly language.
Treating assembly as a high-level language.
Put it right: It is low-level and hardware-specific, using mnemonics for individual instructions.
Exam tips
- State the translator name (assembler) and the one-to-one relationship in the same answer.
- Use the phrase 'one machine code instruction per line' to show the mapping precisely.
- Contrast briefly with high-level languages to demonstrate understanding of the difference.
Try the lesson
The start of the Classification of programming languages and translators: each line of assembly language is assembled into a single machine code instruction lesson, made from checked teaching notes for this specification point.
Have a go first
An assembler translates a program written in assembly language. What does each line of the assembly language program become after assembly?
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