A microprocessor unit, a memory unit, and an input/output unit form a -

Microcomputer, an electronic device with a microprocessor ;as its central processing unit (CPU).
The microcomputer was formerly a commonly used term for personal computers, particularly any of a class of small digital computers whose CPU is contained on a single integrated semiconductor chip.
Thus, a microcomputer uses a single microprocessor for its CPU, which performs all logic and arithmetic operations.
The system also contains a number of associated semiconductor chips that serve as the main memory for storing program instructions and data and as interfaces for exchanging data of this sort with peripheral equipment—namely, input/output devices (e.g., keyboard, video display, and printer) and auxiliary storage units.
Source: Britannica