Difference Between RTOS and OS

RTOS vs OS

Most of us are familiar with the OS or operating system that we use on our computers. The most common operating system for personal computer include Windows from Microsoft, OS X from Apple, and the wide variety of Linux variants that can be obtained from their respective developers. What most people do not know are Real-time Operating Systems or generally referred to by the acronym RTOS. These are operating systems that are used for more specialized applications that demand response that is as close to real time as possible. The most significant difference between the two is in how they approach each task. Standard operating systems focus on doing as much computation in the shortest span of time while RTOSes emphasize on having a predictable response time.

Standard operating systems are widely used nowadays, partly due to the rapid spread of personal computers. Devices that use standard operating systems, aside from computers and laptops, are also beginning to appear. RTOSes are used in more specialized fields where the response time is much more important than the ability to process a huge number of instructions within a given time span. Examples of which are computer that scan levels and states in a facility. It is important that the monitors see changes occur at the instant that they do.

Most operating systems use a time sharing architecture where each task is assigned a small slice of time to execute its instructions before switching to another task. The switching process is too fast that it often appears as real time to users. Some RTOSes also use this design but with much lower density of tasks to ensure that the processor never gets to loaded, which can increase the response time. Another design that is used for an RTOS is an event-driven architecture. In this design, the system only switches tasks once an event or interrupt occurs.

Coding practices for an RTOS is much stricter compared to a standard OS as the code needs to perform consistently all the time. Standard OSes are not that concerned since response time is not of great importance in its application.

Summary:
1. A regular OS focuses on computing throughput while an RTOS focuses on very fast response time
2. OSes are used in a wide variety of applications while RTOSes are generally embedded in devices that require real time response
3. OSes use a time sharing design to allow for multi-tasking while RTOSes either use a time sharing design or an even driven design
4. The coding of an RTOS is stricter compared to a standard OS

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