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real time operating systems

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Jul 25, 2007
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hi friends
what is real time operating systems?
how it is related with embedded systems?
is there any relation b/w both?

tell me please:D

all embedded systems are real time systems... real time system is what is actually being used by the people... embedded system is a system in which the hardware is the main part and nothing more can be added in terms of software....

hi all
i want real time operating systems,please tell me clearly

Real time os mean the os that operate the task in constrain time.
RTOS is the os that combined with some embedded system to provide the real- time capabilities.

You can search for the definition of read-time os on

the hardware inside mixie, washing machine and all other household electronics are examples of real time OS... they perform task within a constrained time...

real time systems are those which can be operated in day to day use over comin the practical constrains.

in terms of embedded systems....say any process should only take a fixed or only some fixed amount of time to execute. if not there is no point usin it. hence, its not a real time system....

One important aspect of RTOS is that a response should be provided within a limited time, otherwise, even correct response is viewed as wrong. From this perspective, RTOS can be substantially different from the usual OSes.

os which takes decision in real time means no delay.
looping ,delay are avoided in RTOS.

Not to want to disagree with prior definitions of RTOS but I think being an old fart that I can give another definition more from a historical basis.

Early computer operating systems worked mostly in a "Batch" environment. User jobs were processed sequentially one at a time, having to wait their turn for execution. Application programs would be loaded, run and then dumped for the next job by the OS job scheduler. Typically the OS could only run one user program at a time.

As computers became more powerful and useful for more applications there became a need for operating systems that could execute many user programs already loaded into memory, in a more flexible and timely matter. Such RTOS could load programs and assigned them a priority level that would ensure that they would execute when required to respond to external interrupts or when hardware services became available to them, otherwise they were just given a time slice for normal execution depending on their priority.

Later there was a term coined 'deterministic' to describe an OS systems that could guarantee a certain response time for any specific applications. This I think is a good current definition of a RTOS.


Dear friends,
i want to learn Embedded systems & RTOS from basics? can anyone tel from which website i can learn.. Also wat is the knowledge required to learn Embedded systems &RTOS. PLz reply..

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