What is the definition of an RTOS?

[cameo_2007]

what is an RTOS.Why it is called so? pls specify with an example..
Which are the RTOS s/ws available?

thanks

 

[kumi19]

what is rtos

RTOS is realtime operating system...which is very time critical the response from the rtos should be in the specified time limit..real time has can be classified has hard realtime and soft real time systems...
in hard real time the response should be within the time limit whereas in soft real time systems it can devaite frm the specified time limit...
for more information u can refer REAL TIME SYSTEMS by JANE W.S.LIU
u can log on to freertos.org

to name a few different rtos available are nucleus,rt linux,threadx,posix,ucos etc

 

[ariyan]

Re: what is RTOS??

A system in which the timely completion of tasks is important. A delayed response is as good as a bad response !

Real-time systems satisfy a completely different set of requirements. A real-time system must never be overloaded. As soon as no more processing power is available, real-time response cannot be sustained.

For example, a situation with real-time requirements might be: a meter generates data every second. The data must be collected, processed, and stored by the computer. If processing a data record requires more than a second on the target computer, the system is overloaded and real-time response cannot be sustained.

Added after 4 minutes:

Sorry for break due to some proxy problem:

Types of Real-time systems : Hard & soft

Hard real-time systems : Are systems in which system reponse time is very critical. Even a small delay in the response time can be fatal or destructive

e.g. : ABS system in vehicles, Flight controller systems, Heart pacemaker

Soft real-time systems : Are systems in which task response, if delayed, is tolerable within a certain limit.

E.g. : Engine control units in vehicles,

So, with so many off-the-shelf RTOS available, which one & how should you choose one ( or, on second thoughts, make one of your own ? ) ?

RTOS, typically, are an expensive lot & cost anything between USD 10 K upto USD 50 K ( runtime royalties not included ! What's that ?? ). Therefore, choosing the right one is important

A low budget RTOS might not burn your pocket, but will come with only a basic scheduler & few other system calls. Some of these also include the source code.
For e.g. Accelerated Technology's Nucleus, kadak's AMX etc.

The fully blown ( & the expensive ones ) typically include a lot of useful functionality beyond just the scheduler. They also assure you of a better real-time performance.

The higher price often includes free technical support, training & a set of integrated development tools. E.g. VxWorks by Eindriver Systems, Integrated Systems pSOS, Microtec's VRTX etc.

 

[dragonight_x]

Re: what is RTOS??

RTOS is short for Real-Time Operation System, A real-time operating system (RTOS) is a multitasking operating system intended for real-time applications. Such applications include embedded systems (programmable thermostats, household appliance controllers, mobile telephones), industrial robots, spacecraft, industrial control , and scientific research equipment.

An RTOS facilitates the creation of a real-time system, but does not guarantee the final result will be real-time; this requires correct development of the software. An RTOS does not necessarily have high throughput; rather, an RTOS provides facilities which, if used properly, guarantee deadlines can be met generally (soft real-time) or deterministically (hard real-time). An RTOS will typically use specialized scheduling algorithms in order to provide the real-time developer with the tools necessary to produce deterministic behavior in the final system. An RTOS is valued more for how quickly and/or predictably it can respond to a particular event than for the given amount of work it can perform over time. Key factors in an RTOS are therefore a minimal interrupt latency and a minimal thread switching latency.

 

[SmartBomb1979]

Re: what is RTOS??

Beeblebrox,

Way to simply quote Wikipedia. For crying out loud, you didn't even remove the meta-information embedded in the text!

Next time either just post the URL or at least give credit to the original source, OK?

en.wikipedia.org/wiki/RTOS