Computer on a single chip is called

Whether a piece of computing hardware or software counts as “a computer on a single chip” depends on the level of integration: a genuine single-chip computer must house the processing core, working memory, and input/output interfaces together on one integrated circuit, so it can operate as a self-contained system without needing extra external chips. A component that provides only the processing core, or a tool that exists purely as software, does not meet that bar.

A microcontroller is exactly this kind of device: it integrates the processor, working memory, and input/output peripherals onto a single chip, so it functions as a complete, self-contained computer without needing any external memory or I/O hardware.

• Microprocessor: contains only the central processing unit; it must be paired with separate external memory and I/O chips before it can work as a computer, so on its own it is not a complete single-chip computer.

• Assembler: a software program that translates assembly-language instructions into machine code; it is not hardware at all, so it cannot be “a computer on a single chip” in any sense.

• “More than one of the above”: would require two or more of the listed terms to equally match the definition, but each names a distinct, non-overlapping concept, so at most one can be the precise match.

• “None of the above”: would require that no listed term match the definition, but one of the specific hardware terms already satisfies it exactly, so this option cannot hold.

Cross-checking against the standard computer-organization definition — a small computer on a single integrated circuit combining a processor core with memory and programmable I/O — confirms the same result: the term for a computer on a single chip is microcontroller, not microprocessor (CPU only) or assembler (a software tool).