Basic Classifications of Real-Time Operating Systems

March 1st, 2017 by

Real-time operating systems, or RTOS, are designed to automate and accelerate the process of decision-making in order to avoid an unwanted outcome. An RTOS may support very simple tasks or extremely complex procedures. Regardless, you need to know what kind of real-time operating system best suits your situation to achieve your desired results.

3 types of real-time operating systems

Operating systems are extremely customized. It is therefore almost impossible to find two similar systems in different environments. However, there are three major classifications determined by the mode of operation.

  • Hard RTOS. A hard RTOS is distinguished by its strict adherence to the deadline or limits of the task stipulated. In case this deadline is missed, the results are catastrophic. For example, an airbag has to deploy within the perfect time frame. Failure to deploy may cause death or extreme destruction. It means that the deadline was missed.
  • Firm RTOS. With a firm RTOS, the need to stick to the deadline does not have a catastrophic effect but the results are undesirable. An example is a production plant where the quality of a product diminishes because the deadline was not met. This will affect the reputation of the brand, profits, etc.
  • Soft RTOS. The effects of missing a deadline with a soft RTOS are not as catastrophic as in the two previous cases. The processes can be reversed or corrections made without much effect on the product or process. An example is the creation of a database that is used for storage purposes.

3 core features of real-time operating systems

No matter which type of RTOS you choose, the basic design should consider optimal deployment time and predictability. To this end, a real-time operating system requires a variety of key features, including:

  • A short context switching latency: it should take the least time possible to save data for the current context in order to switch to the current one.
  • Short interrupt latency: this is the time taken to interrupt a task, switch it off and activate the next one.
  • Consistent and reliable timing: there should be no delays in switching between tasks. There will be complications if one task ends early or another is delayed waiting for something else to be completed.

Real-time operating systems are usually highly personalized. Even so, it’s important to understand the basic types of RTOS and core functionality to ensure you select the best system for your business.


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