What are real-time operating systems ? Pay attention to a detailed study of RTOS. First of all, these are special types of operating system that differ from universal OS in their performance and speed in the worst situations. There are many concepts that reveal specifics:
- RTOS - a system that is able to provide the necessary service for a certain period of time;
- a real-time system that is distinguished by constant availability and the time of the processed information is invisible to users;
- “fast system”, where not the response time of the RTOS comes to the fore, but the sufficiency of time to work with the application.
For completeness, it is worth paying attention to the characteristic features of real-time operating systems. The most important feature is a guaranteed and stable response to events. Tasks of any level (high and low priority) should not conflict with each other and crowd out each other. High level of requirements for response time to a specific event in real time.
Types of real-time operating system
They are divided depending on the programs: hard (hard), soft (soft) and interactive. Briefly consider each view.
Rigid RTOSs have a strictly defined real-time response time to an event. Example: hardware interruption, the display of control commands must be processed for a certain time, which happens in 100% of cases.
Soft real-time systems allow in 80-90% of cases to deviate from certain time frames by one order of magnitude. But the main thing is that these delays do not lead to irreparable consequences.
Interactive RTOS includes the human factor (when an individual expects a response from the system after instructions or commands are given by him).
The most common real-time operating systems and their characteristics
Most RTOS are closed-type, and it is difficult to obtain detailed information about them. WindRiver Systems has developed VxWorks (Rigid RTOS) for developing software on embedded PCs. It is based on the work of the host computer, which is developing software, and the client computer, where it is used under the control of VxWorks.
These real-time operating systems are widely customizable, but software modules cannot be used in another environment, which makes them quite limited in use. The benefits include:
- Unlimited number of tasks.
- The number of priority tasks is up to 256.
- Tasks are planned cyclically or by priority.
- Semaphores that help manage critical system resources.
QNX Neutrino Realtime Operating System is the brainchild of QNX Software Systems. It is based on a cross-server architecture and is highly multitasking with priority mode. Each element of the system works independently: in case of failures and malfunctions, any link can restart itself without affecting the operation of the kernel or other components. It also has a deep configuration, binding to the base core, which excludes work in another environment.
ChorusOS presents an example of an embedded OS that is widely used in telecommunications. It supports various telecommunication protocols, Java-technology, which allows you to introduce new developments and applications.
Unlike general purpose and general purpose OS
OSRVs differ from general-purpose systems in the deterministic nature of work, which is due to strict control of the time spent on processing tasks. The concept of “determination” describes a predetermined time interval for which one real-time program is executed.