What is a Real-Time Operating System and What Does It Do?



What’s the difference between a real-time operating system versus a regular operating system?

Operating systems – they’re a standard feature of devices in the digital age. Whether it’s the Windows system installed on your PC or the Mac system installed on your Apple notebook, there are a few common operating systems (OS) choices everyone knows.

There have been various spin-off systems as well. One example is the Chrome OS, which is used for a minimalist purpose on the Chromebook device line. Even Linux, an open-source system, has gained a lot of popularity throughout the decades despite less mainstream support than proprietary competitors.

But what exactly is an operating system? In short, it is the main software interface that communicates with hardware devices and enables the user to control the entire system. It’s the portal through which we use devices, and it’s one of the most important aspects of modern technology. Evolving from batch processing in the 1960s, operating systems have come a long way.

Every operating system is designed to handle a certain number of tasks and process them in a certain time frame. This means most of them to have room for a little buffer delay, and are pretty straightforward when it comes to processing the order of tasks.

But what about for systems that need to process information in real-time? This is where a real-time operating system (RTOS) comes in handy. But what exactly do these systems entail, how do they work, and what are some real-world examples of RTOSs?

What Exactly is a Real-Time Operating System?

Think about the standard features of any operating system. For reference, use Windows or Mac. The convenient design makes it easy for you to find your way around the system. The software setup is integrated to control and interact with the hardware and facilitate normal functions.

But some applications need to process data without buffer delays. They need to respond to inputs as they arrive, rather than scheduling them according to a pre-determined schedule like normal operating systems. This is the definition of a real-time operating system.

An RTOS typically measures its response times in smaller increments than normal operating systems. For example, a standard computer with a Windows or Mac OS may count the seconds it takes to load a single program from a user input. But for a real-time operating system, they’ll use tenths of seconds or in some cases even smaller units of time to measure delays.

Technically, a real-time operating system still has delay just like a standard operating system. The difference is the OS delay for the real-time systems are (or should be) much less than those in standard systems.

Deadlines are more crucial, the margin for error is much slimmer, and the needs of the system are much different. These are the characteristics of a real-time operating system – but where can a person find these types of systems in the real world?

There are many places where real-time operating systems are used. They’re often created solely to handle needs that traditional operating systems won’t work for.

Where Are Real-Time Operating Systems Used?

For some people, their line of work requires them to use certain software and hardware that isn’t exactly common. Their unique nature means they have their own drivers, their own commands, and even their own compatibility issues when paired with mainstream systems.

Pairing these programs and peripherals with a system designed specifically for them is much more effective. In many workplaces, a real-time operating system is the choice tool for handling time-sensitive issues and making sure programs and devices work smoothly.

Take for example the job of being an airline pilot or even an air-traffic controller. These types of tasks have unique requirements in terms of both the hardware and software they use. The needs they have are some that most people will never think of. Because of this, standard operating systems won’t suffice, and real-time operating systems are needed instead.

These systems are used for air traffic systems, medical facilities’ computer portals, and even in the networks of scientific laboratories. Another benefit of these systems, besides their unique nature and ability to be used for special situations, is their speed.

Real-time operating systems are helpful in situations where an instant response is needed. Whereas normal operating systems have their own methods for scheduling task execution, which can leave some commands being processed seconds or minutes after being inputted.

But think about that in the context of someone trying to land a plane in rough weather, or trying to mix medicines where milliliters and milliseconds matter. Obviously, there is little room for delay in these situations. Time is more important, so operating systems must be configured to read commands and respond quickly.

Why have RTOS models evolved so much over time? The answer is because the industries that use these systems need the most reliable solutions available and because downtime can become a bigger issue over time.

What Are the Dangers of Slow Response Times?

When a person is using a standard OS and there are some delays, it’s usually only frustrating and not disastrous. Sure, a person may miss out on an important conversation or fail to get some work turned in on time – but it usually doesn’t lead to anyone taking a major monetary loss or sustaining serious damage to persons or property.

The same can’t be said in situations where RTOSs are used. In these situations, a little bit of downtime can result in a lot of harm done. If a plane is trying to land in a storm and the process of giving them proper coordinates takes a few minutes or even seconds longer than expected, it can lead to a crash.

Likewise, someone in the medical field may incur massive amounts of liability if their system’s delay causes medicines to be mixed improperly. This could cause a patient to suffer serious side effects, meaning accuracy matters above all in these situations, thus why the RTOS is used.

It’s somewhat of a continual cycle – as RTOS options improve, industries that use them can promise more accuracy and quickness. But, as those promises increase, they are also pressed to improve their systems even further to help find ways to continue the error-proofing process.

Slow response times can be the downfall of anyone, especially in industries where time is a very crucial factor. While one could argue every user has a high time-preference when it comes to their OS’s responsiveness, there’s no denying some tasks are more demanding than others.

A Field with Its Own Vernacular?

Given that the real-time operating system model is unique and is much less prominent than standard OSs, it stands to reason that these systems have their own unique terminology. Understanding these terms and concepts is important to those who work with real-time operating systems on a regular basis.

Here are some of the basics:


Can an RTOS guarantee a certain response time within a given margin for error? This is important for determining whether the application or parts of it are robust enough for a task. If a system or part of it can offer guaranteed timing including accuracy regarding the standard margin of error, that system is referred to as deterministic.

Soft vs. Hard Real-Time

How is the response time in an RTOS measured? If the creators of the system can guarantee a max window of time upon an inputted command, the system is referred to as a hard real-time system. If they can guarantee the timing according to a certain margin of error, the system is referred to as a soft real-time system.


Sometimes the same task may need to be executed again and again. But even in the most reliable systems, there can be a little bit of timing discrepancy over various iterations of the same program or application launch. This discrepancy in timing is referred to as jitter.

These are just some of the terms a person may need to know if they’re working with an RTOS. Learning these terms and what they mean makes it easier to work with, configure, and understand these systems on a deeper level.

The Future of the RTOS: Can It Influence the Normal OS?

While the reliability of the real-time operating system is something that the normal OS just doesn’t have, there is a chance this could change in the future. Normal operating systems could become more inspired by their real-time counterparts, and look to minimize delay.

But if the technology is growing to the point that normal operating systems will begin functioning with the speed of current real-time systems, actual real-time systems may evolve as well. They’ll likely become even faster and offer even smaller margins for error, making them viable in even more applications.

Most people have heard of operating systems, so they already know the basics of an RTOS without even realizing it. The difference is in the name – these systems are geared toward quick responses, small margins for error, and unmatched efficiency no matter what field they’re used in.




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