What is real-time operating system (RTOS)?

A real-time operating system (RTOS) is an operating system (OS) intended to serve real-time application process data as it comes in, typically without buffering delays.

A common example of an RTOS application is an HDTV receiver and display. It needs to read a digital signal, decode it and display it as the data comes in. 

Who need real-time operating system?

In many cases, there is little argument. When designing a flight control system, medical instrument, or process control application, for example, most system designers will choose an RTOS, simply because these systems must meet absolute deadlines.

Types of real time operating system -

1. Vx Works:

 VxWorks is a real-time operating system (RTOS) that can be used in embedded systems. VxWorks can be customized easily and can run on most processors designed for distributed computing. VxWorks is used to control network and communication devices, test and measurement equipment, computer peripherals, automotive systems, avionics (aeronautics and astronautics) equipment and diverse consumer products.

2. RT linux : 

RTLinux is a hard real time RTOS micro-kernel that runs the entire Linux operating system as a fully preemptive process. The hard real-time property makes it possible to control robots, data acquisition systems, manufacturing plants, and other time-sensitive instruments and machines from RTLinux applications.

3.MU linux :

The name muLinux comes from the Greek letter mu which is the SI symbol meaning one millionth, harking to the very small size of this OS. muLinux was based on the Linux 2.0.36 kernel.Development was frozen in 2004 at version 14r0, with some of the code and packages taken from software releases going back to 1998 (owing only to their smaller sizes). An experimental, unstable version called Lepton had the 2.4 kernel.