Multitasking operating system used for real time applications.
What is an RTOS?
It consists of two parts : Real Time & Operating System
Real Time:-
Real-Time indicates an expectant response or reaction to an event on the instant of its evolution. The expectant response depicts the logical correctness of the result produced. The instant of the events’ evolution depicts deadline for producing the result.
Operating System:-
To run a single program is easy.
What to do when several programs run in parallel?
We need several other features like :-
Memory areas
Program counters
Scheduling (e.g. one instruction each)
Communication/synchronization/semaphors
Device drivers etc
OS is a program offering the common services needed in all applications. It provide
Environment for executing programs, Support for multitasking/concurrency, Hardware abstraction layer (device drivers), Mechanisms for Synchronization/Communication , Filesystems/Stable storage etc.
OS is commonly equipped with features like: Multitasking, Synchronization, Interrupt and Event Handling, Input/ Output, Inter-task Communication, Timers and Clocks and Memory Management to fulfill its primary role of managing the hardware resources to meet the demands of application programs.
So RTOS is an operating system that supports real-time applications and embedded systems by providing logically correct result within the deadline required. Such capabilities define its deterministic timing behavior and limited resource utilization nature.
Hard real-time: degree of tolerance for missed deadlines is extremely small or zero. A missed deadline has catastrophic results for the system. Examples include the safety critical systems and are related to sensing, actuation and control activities, Airbag in Car.
Firm real-time: producing the results after its deadline is useless for the system, but does not cause any damage. Examples can be found in networked applications and multimedia systems, where skipping a packet or a video frame is less critical than processing it with a long delay.
Soft real-time: deadlines may be missed and can be recovered from. Reduction in system quality is acceptable. Examples : handling input data from the keyboard, saving report data etc
Applications that require real-time computing include the following:
Chemical and nuclear plant control, control of complex production processes, railway switching systems, automotive applications, flight control systems, environmental acquisition and monitoring,
telecommunication systems, medical systems, industrial automation, robotics, space, military etc.
Comparison of GPOS and RTOS: Click here
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