Assemblers and compilers translate their input into machine code directly

The idea

An assembler takes assembly language (low-level, mnemonic-based) as input and translates it directly into machine code, producing an object file the processor can run. A compiler takes a high-level language program as input and translates the whole program into machine code in one go, also producing an object file before execution. The key point is 'directly': both produce machine code without a separate interpretation step at run time. Contrast this with an interpreter, which translates and executes line by line and does not produce a standalone machine-code file. So the shared feature is that assembler and compiler output is machine code.

What earns the marks

• An assembler translates assembly language into machine code.
• A compiler translates a high-level language program into machine code.
• An interpreter differs because it translates and executes line by line rather than producing machine code directly.
• Machine code consists of binary instructions the processor can execute.

Common mistakes and how to put them right

• Saying a compiler interprets the program line by line.

  Put it right: A compiler translates the whole program into machine code before it runs.

• Confusing an assembler with an interpreter.

  Put it right: An assembler converts assembly language into machine code; an interpreter executes source code line by line.

• Claiming a compiler produces high-level source code.

  Put it right: Its output is machine code.

Exam tips

• State the input and the output for each translator to earn clear marks.
• Use the word 'directly' to distinguish assembler and compiler from interpreter.
• Link machine code to binary instructions the CPU can execute.