Real Time Operating System (RTOS)

Real-Time Operating System (RTOS)

A real-time operating system (RTOS) is a type of operating system. An operating system is basically, a program that acts as an interface between the system hardware and the user. Moreover, it handles all the interactions between the software and the hardware.

The real-time operating systems are used in real-time systems where the time constraints are fixed and followed strictly. This means that the time for processing and responding is very small. Moreover, the system should perform the given task in a fixed time otherwise, it results in a system failure.

Response Time is the time within which the system takes the input, processes the data, and gives the results. Moreover, they are used in systems like robots, missile launches, airplanes, etc.

Types of RTOS

There are three types of real-time operating systems. They are as follows:

1. Hard Real-Time Systems

In this, the time constraint is very short and strict. Even seconds of delay is not acceptable. Therefore, it is compulsory to complete the task within the given time only.

Examples are Airplanes systems, Medical treatment systems, etc.

2. Firm Real-Time Systems

In these systems, although the deadline is given but, missing them does not result in great loss. There can be some unwanted side effects in the system if the deadline is not followed.

Examples are multimedia systems.

3. Soft Real-Time Systems

As the name suggests, the system handles the deadlines softly. This means that if there are small delays in the system, it is acceptable.

Examples are Online Transaction systems, Livestock price quotation systems, Computer games, etc.

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Difference Between Hard and Soft Real-Time Systems

The differences between hard real-time systems and soft real-time systems are as follows:

Hard Real-Time System	Soft Real-Time System
These systems have to follow the deadline very strictly.	These systems do not have fewer restrictions on the deadline.
The size of the data file is either small or medium.	On the other hand, soft real-time systems have large data files.
The response time is in milliseconds.	Comparatively, the response time is higher.
These systems strictly emphasize safety.	Safety is not so strict in these systems.
Examples are satellite launch systems, missile launch systems, Railway systems, etc	Examples are computer games, online transaction systems, etc.

Difference Between Firm and Soft Real-Time Systems

The differences between firm real-time systems and soft real-time systems are as follows:

Firm Real-Time System	Soft Real-Time System
The system should complete the task before the deadline.	It also has to complete the task within the deadline but, not strictly.
In case, it gives the results after the deadline it has zero importance.	If it gives the results after the deadline, the importance decreases and slowly goes to zero value.
If the results are given after the deadline, they are considered as incorrect.	On the other hand, even if the system gives the results after the deadline they are not considered incorrect.
Multimedia applications use such systems. Practical systems make less use of them.	It is mostly used in practical applications.
Examples are multimedia systems etc.	Examples are computer games, online transaction systems, etc.

Parts/Components of RTOS

The important parts of a real-time operating system are as follows:

1. Scheduler

It decides the order in which the tasks will execute. Moreover, it decides the order based on the priority of each task.

2. Memory Management

It allocates memory to every program. Hence, it is one of the most important elements of the system.

3. Symmetric Multiprocessing (SMP)

It is the multiple different tasks that an RTOS can handle inorder to perform parallel processing.

4. Function Library

It helps to send the requests from the kernel to the application to produce the output, using the function library. Thus, it is an interface between the kernel and the application code.

5. Fast Dispatch Latency

It is the interval between the termination of one task and the starting of execution of another ‘ready’ state task.

6. User-defined data objects and classes

RTOS makes use of programming languages like C, C++, etc. that are organized with respect to their operations. The user should define object sets to organize them. The system uses these sets to control the application.

Advantages of RTOS

• They have no errors.
• Due to their small size, they can be easily added to other systems.

Disadvantages of RTOS

• Algorithms are complex.
• System resources are expensive.

Frequently Asked Questions (FAQs)

Q1. What is the full form of RTOS? What is its function?

A1. RTOS stands for Real-Time Operating System. This type of OS is used in real-time situations where time constraint is very strict.

Q2. What are the types of RTOS?

A2. There are three types of RTOS. They are as follows:

1. Hard Real-Time Systems

In this, the time constraint is very short and strict. Even seconds of delay is not acceptable. Therefore, it is compulsory to complete the task within the given time only.

Examples are Airplanes systems, Medical treatment systems, etc.

2. Firm Real-Time Systems

In these systems, although the deadline is given but, missing them does not result in great loss. There can be some unwanted side effects in the system if the deadline is not followed.

Examples are multimedia systems.

3. Soft Real-Time Systems

As the name suggests, the system handles the deadlines softly. This means that if there are small delays in the system, it is acceptable.

Examples are Online Transaction systems, Livestock price quotation systems, Computer games, etc.

Q3. List the parts of RTOS.

A3. The components of the RTOS are as follows:

• Scheduler
• Memory Management
• Symmetric Multiprocessing
• Function Library
• Fast dispatch latency
• User-defined data objects and classes

Q4. What is the difference between hard and soft real-time operating system?

A4. The main difference between hard and soft RTOS is that in hard RTOS the time constraint is strictly followed whereas, following the deadline is not so strict in the soft RTOS.

Q5. Give advantages of RTOS.

A5. Advantages are:

• They have no errors.
• Due to their small size, they can be easily added to other systems.