What characterizes a multiprocessor computer system?

A multiprocessor computer system is characterized by having multiple processing units, which can work simultaneously to perform tasks, leading to improved performance and efficiency. The presence of multiple processors allows for parallel processing, meaning that different processes or threads can be executed at the same time. This capability enhances computational speed and is particularly useful for high-performance computing tasks, intensive data processing, and multi-user environments.

In contrast, a system with one processing unit would not qualify as a multiprocessor system, as it lacks the ability to perform multiple operations concurrently. A system with no processing units would not be functional for data processing tasks, and the term "virtual processing units" typically refers to software-based abstraction rather than physical processors, which does not fit the definition of a multiprocessor system. Hence, the key feature of having multiple physical processing units clearly distinguishes a multiprocessor computer system from other types.