What characteristic defines a Real-time Operating System (RTOS)?

A Real-time Operating System (RTOS) is characterized primarily by its ability to execute tasks in a deterministic manner. Deterministic task execution means that the system can guarantee specific timing and performance requirements, ensuring that tasks are completed within defined time constraints. This is crucial in environments where timing is essential, such as in embedded systems for medical devices, automotive systems, or industrial automation.

While some Real-time Operating Systems may have capabilities concerning high graphic performance, support for multiple users, or functioning on low-power devices, these features are not defining characteristics of an RTOS. The essence of an RTOS lies in its task scheduling and prioritization, which are designed to meet stringent timing requirements reliably. Thus, prioritization of deterministic task execution is what fundamentally distinguishes an RTOS from other types of operating systems.