Wht is the actual need of RTOS

[Jack Cawkwell]

Hi,

Angelo, your answer is totally correct, but does not really provide
a complete beginner with an explanation! I am not sure that I have
the experience to give the best answer, but may understand the question
better.

If you run an appication under Linux (for example) the OS with provide
a regular run slot for perhaps 20 or 30 times, and everything will run
as you expected. However after that the system starts running other
programs
which get a higher priority because you have been running for longer,
and so your program runs regulary for a short burst, then stops for a short
time then runs again. This is OK for a normal screen based, or data
processing
application, but if you need a quality of service (qos), which means that
your program is run when required within a specifiable time frame, then you
need to use a real time OS.

Also many realtime applications are embedded, this implies restricted
hardware,
and so it is useful to have a OS cut down to the bare minimum that is
required.
This can be done with Linux (as you have the source and can configure it
any
way you like) but probably not with any M$ OS. So a lightweight OS like
RTEMS
is useful for embedded (or simple apps) just to reduce the hardware
requirement,
even where the qos/RT aspect is not strictly vital.

Perhaps the real experts will correct me if I am wrong?

Jack

angelo_f at bigpond.com writes:
>You didn't actually send this to the whole newsgroup.
>
>gopinandan wrote:
>
>>Hi all
>> I am new into embedded sysytems and would like to know wht is the actual
>>need for RTOS and which is the RTOS that would satuisfyu most of the
>needs
>>in embedded systems
>>Kindly help me out in this regards
>>
>Basically, an RTOS is required when a specification requires that the
>device must meet timing constraints.
>
>-- 
>Angelo Fraietta
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