What is an RTOS - Real Time Operating System (RTOS) | Why RTOS

What is a Real Time Operating System (RTOS)?

RTOS stands for Real-time operating system. Real-time operating system (RTOS) is an operating system (OS), intended to serve real-time applications that process data, typically without buffer delay.

      In Real-time operating system (RTOS) Processing time requirements are measured in tenths of seconds or small increments of time. A real-time system is a time-bound system that has well-defined, fixed times. These types of system, Processing must be done inside defined constraints otherwise the system will fail.

In this article we will know about:

•          What is a Real Time Operating System (RTOS)?
•          Types of RTOS
•          Why use an RTOS?
•          Components of RTOS
•          Features of RTOS
•          What is GPOS?
•          Difference between in GPOS and RTOS
•          Advantages of RTOS
•          Disadvantages of RTOS

Types of Real time operating system (RTOS):-

1.            Hard Real Time
2.            Soft Real Time
3.            Firm Real Time

Hard Real Time (RTOS):

In Hard Real Time (RTOS), All given tasks must be initiated to execute at a predefined scheduling time, and all of their given tasks must be performed within the assigned time period. Because of this, in this RTOS, all deadlines are strictly managed.

For Example: Aero plane Control System, etc.

Soft Real Time (RTOS):

In Soft Real Time (RTOS) may miss its deadline, sometimes with somewhat less probability. Missing the deadline has no harmful consequences. The utility of the result produced by a Soft Real Time system decreases gradually as it increases

For Example: System of Online Transaction, Smart Phones, Telephone’s switch, etc.

Firm Real Time (RTOS):

In Firm Real Time (RTOS) also needs to follow the time limit. However, the disappearance of a time limit may not have a large effect, but may have an undesired effect, like a drastic reduction in the quality of a product.

For Example: Multimedia Products, etc.

Why use an RTOS?

• It is used for ability to separate, which allows separating critical processing from non-critical, which is a powerful tools.
• Abstract time dependence and task-based design result in low interdependencies between modules. This makes for easy maintenance.
• RTOS provides API functions. Which allow for cleaner and smaller application code.
• The work-based system allows separate designers / teams to work independently on their parts of the project.
• Another advantage of modularity is that similar applications on similar platforms will inevitably lead to the development of a library of standard functions.
• Task based APIs naturally encourage modular development because a task will usually have a clearly defined role.

Components of RTOS:-

• Scheduler
• Function Library
• Fast dispatch latency
• Memory Management
• User-defined data objects and classes
• Interrupt Service Mechanism

Scheduler

This is the component of RTOS who describes by order, that which tasks can be execute that are usually on a priority system.

Function Library

This component of RTOS Who works the connection between kernel and application code. This application code send the request to the kernel with the help of function library, and it gives good output as desired.

Fast Dispatch Latency

These types of RTOS component, which maintains the internal gap between termination of the task, which is detected by operating system (OS).

Memory Management

This is the important parts of the RTOS Memory management helps to allocate memory to every program of the system.

User-defined data objects and classes

This component helps to use programming language like C, C++, Java, etc. This helps to increase the efficiency of the entire system.

Interrupt Service Mechanism

The component uses to handle a specific interrupt, it stored in RTOS layers.

Features of RTOS:-

• All tasks are assigned a priority level to facilitate pre-simulation. The highest priority work that is ready to run will be the work that is going on.
• Consume low memory.
• The Kernel reestablishes the condition of the undertaking and passes control of the CPU for that task.
• The Kernel spares the condition of the intruded on task promotion at that point figures out which task it should run straightaway.
• Low Cost.
• RTOS has Unpredictable environment. 

What is GPOS?

GPOS stands for General Purpose Operating System (GPOS). GPOS is an essential program that supports the basic functions of a computer, and provides services for other programs running on the mobile device, server and computers. System Application provides functionality that the user of the computer wants otherwise it’s needed.

Difference between in GPOS and RTOS:-

General Purpose Operating System (GPOS)	Real Time Operating System (RTOS)
It has no any time boundation	It has time boundation
It is designed for multi-user environment	It is designed for single user environment.
It used only for desktop PC and laptop	It is used only Embedded application computing system
It has huge memory	It has less memory as compare to GPOS
Operation of kernel may or may not be preempted	Operation of kernel can be preempted
It contains unpredictable Response Time	It contains predictable Response Time
It has high interrupt latency as compare to RTOS	It has low interrupt latency as compare to GPOS

Advantages of RTOS:-

Here are the advantage of RTOS.

•  RTOS produces more accurate results while achieving maximum consumption of all using resources, so it does not have a down time.
• The time allocation system in RTOS is very excellent.
• RTOS has a very short time frame for transferring all work to its own system.
• It is an error free operating system (OS).
• RTOS can be used in embedded system equipment because it is small in nature.
• RTOS is a more optimizing operating system so it can use O / S in products that are online such as fridges etc.
• RTOS has more systematic memory allocation for every part of the operating system.
• RTOS allows shorter ISRs (interrupt service routines).
• Well-designed inter-work communication.
• In RTOS, each task is executed according to "priority-based scheduling", which means that each task is performed in a predefined time frame.
• It has more maintenance and expansion.
• It has high speed.
• RTOS works on the modularity principle, and because of that principle they help reduce memory dissipation.

Disadvantages of RTOS:-

Here are the disadvantage/drawbacks of RTOS system.

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• A lot of resources are used by RTOS, which makes this system expensive.
• RTOS requires specific drivers so that it can offer a faster response time to interrupt the signal, helping to maintain its speed.
• It uses complex algorithms that are difficult to understand.
• Minimal switching of tasks is done in real time operating system.
• RTOS uses a lot of resources, which are sometimes not suitable for the system.
• Functions that have lower priority need to wait longer because RTOS maintains the accuracy of the program, which are subject to execution.
• The RTOS system can run minimal tasks simultaneously, and it only focuses on applications that contain errors so that it can avoid them.
• RTOS is the system that focuses on certain tasks. Therefore, multi-tasking is really difficult for these systems.