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guzhal
Joined: 24 Feb 2007
Posts: 30
Helped: 1
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 25 May 2007 15:10 difference in real time systems |
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what is a hard real time system and soft real system
which OS will come under hard real time and which will come under soft real time
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cfant
Joined: 04 Apr 2001
Posts: 170
Helped: 18
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| 25 May 2007 20:36 Re: difference in real time systems |
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| Difficult to say. Depends on your timing requirements. Usually, vxWorks, pSOS etc. and other RTOSes are considered hard-realtime OS.
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guzhal
Joined: 24 Feb 2007
Posts: 30
Helped: 1
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| 26 May 2007 13:11 Re: difference in real time systems |
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| can u pls. tell me about MicroCOS II .I know that it is a time deterministic OS ,means a hard real time but sometimes it is called as soft real time why?
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cfant
Joined: 04 Apr 2001
Posts: 170
Helped: 18
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| 29 May 2007 8:52 Re: difference in real time systems |
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Deterministic means that interrupt latency is constant, and doesn't depend on the system load. Here is the definition of the hard real-time vs soft real-time (from Wikipedia):
A system is said to be real-time if the correctness of an operation depends not only upon the logical correctness of the operation but also upon the time at which it is performed. The classical conception is that in a hard or immediate real-time system, the completion of an operation after its deadline is considered useless - ultimately, this may lead to a critical failure of the complete system. A soft real-time system on the other hand will tolerate such lateness, and may respond with decreased service quality (e.g., dropping frames while displaying a video).
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sudhavanib
Joined: 28 May 2007
Posts: 6
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| 02 Jun 2007 11:12 Re: difference in real time systems |
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both HARD real time systems and soft real time systems have time constraints,
but the difference is if in hard real time systems if the system does not met the time constraints then there will be fatal damage for both users and machinery.missile applications,medical equipments such as artificial life machine comes under this hard real time systems.
but in soft real time systems missing the time constraints for some seconds there will not be any serious damage.
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ashad
Joined: 28 Mar 2006
Posts: 303
Helped: 9
Location: Singapore
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| 04 Jun 2007 12:15 Re: difference in real time systems |
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| QNX Real time OS
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asprakash
Joined: 20 Nov 2006
Posts: 35
Location: Chennai, India
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| 07 Jun 2007 15:22 Re: difference in real time systems |
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MicroC os is a is a low-cost priority-based pre-emptive real time multitasking os limited feautures compare with above RTOSs like Vxworks, Psos,QNX...
Good for beginners and RTOS learners and U can download it from Micrium site.
uC/OS-II is currently maintained by Micrium Inc.
http://www.micrium.com/products/rtos/ucos-ii_view.html
-----------------
Prakash.
http://electronica.org.in
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saubhik
Joined: 27 Apr 2007
Posts: 108
Helped: 3
Location: Mumbai
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| 02 May 2008 7:18 Re: difference in real time systems |
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| Go For the Site http://zone.ni.com/devzone/cda/tut/p/id/3938
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bharaths_jois
Joined: 28 Dec 2006
Posts: 12
Location: Bangalore,Karnataka,India
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| 03 May 2008 15:39 Re: difference in real time systems |
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Hi,
Hard real time systems and soft real time systems are as the name goes "real-time systems". The noticeable difference between these both is that -
A hard real time system HAS to meet the deadline EVERY TIME, and the completion of a task after the specified deadline is useless and unacceptable.
Eg: ABS in a car is hard real time system, whose "not meeting the deadline of providing required deceleration as soon as the break pedal is pressed" is useless.
A soft real time system is one which need not always meet the deadline and the delay in its response is acceptable (Well... Not always I would say).
Eg: A CODEC in our cell phone missing a few incoming frames from the network is acceptable (since the deterioration in the speech quality is not very much).
Hope this has helped you out.
Regards,
Bharath
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