What are the best resources for learning about RTOS?

An RTOS (real-time operating system) is an operating that guarantees a certain capability within a specified time constraint. You can learn RTOS by joining some RTOS Training. If you don’t have the time to go for training, then you can buy books on RTOS or can learn RTOS online. There are many sites which provide the online tutorial on RTOS. Here's a brief overview on RTOS for those that don’t want to commit to a book or code just yet.

What is RTOS?

An RTOS comprises of two components: Real Time and Operating System. An Operating System is nothing but a collection of functions which provides an interface between hardware and application programs.Real-time systems are those systems in which the correctness of the system depends not only on the logical result of computation, but also on the time at which the results are produced.Hence, RTOS is an operating system that supports real-time applications by providing logically correct result within the deadline required. Some of the most widely used RTOS are: Lynx OS, RT Linux, OSE, QNX, Vx Works and Windows CE. Some of the examples of RTOS are:

• Airlines reservation system.
• Systems that provide immediate updating.
• Air traffic control system.
• Systems that provide up to the minute information on stock prices.
• Defense application systems like as RADAR.

PRIMARY FUNCTIONS OF RTOS

The primary functions of the real time operating system are:

• Manage the processor and other system resources to meet the requirements of an application.
• Synchronize with and respond to the system events.
• Transfer the data efficiently among processes and to carry out coordination among these processes.

BASIC FUNCTIONALITIES OF RTOS

An RTOS has to provide 3 essential things:

• Task Scheduling - The scheduler determines which task to run and when a task will run
• Task Dispatching - The dispatcher handles the necessary operations to get a task ready to go
• Inter task Communication - This is the mechanism that handles how you exchange data and information between tasks and processes on the same machine or from other machines

RTOS CLASSIFICATION

RTOS can be classified into following categories based on the degree of tolerance in meeting the deadlines:

• HARD RTOS: This type of RTOS strictly follows the deadline associated with the task. A missed deadline can result in catastrophic failure of the system
• FIRM RTOS: If such type of RTOS misses the deadline, it will not result in catastrophic failure of the system but could cause undesired affects, like reduction in quality of a product.
• SOFT RTOS: Such type of RTOS can miss the deadline occasionally but system doesn’t fail.

RTOS FEATURES

Some of the features of RTOS are described below:

• Context Switching, that is, the time taken while saving the context of current task and then switching over to another task should be short.
• The time taken between executing the last instruction of an interrupted task and executing the first instruction of interrupt handler should be predictable and short.
• An RTOS should have support for multitasking and task preemption.
• Reliable and time bound inter process mechanisms should be in place for processes to communicate with each other in a timely manner.
• Real time Operating systems but support kernel preemption where-in a process in kernel can be preempted by some other process.

The Author is an IT professional and a writer having more than 5 years experience in his field.