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Diff Between RTOS & Normal OS

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ahmed osama

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Jul 18, 2004
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rtos vs os

hi all

what is the diff between RTOS and Normal OS

many say RTOS is design speical for embedded system

now if i imagine i could put winXP in a camera processors with P4 3.5GH will this not be enough??

so what all says??


difference between gpos and rtos

The important feature of an RTOS is that it will complete a command within a specified time period, whereas Windows for example, will perform an instruction when it's good and ready.

rtos vs normal os

RTOS : Time based scheduling.. A process shud be completed in specific time.. so we need to be efficient in programming / scheduling.. Tats y kernel differ..
example : VDK,uLinux,

Normal OS .. is process based scheduling ,.. No need of time specific..

Example Windows/Linux

difference between rtos and gpos

Hi Ahmed,

The difference between an RTOS and a general purpose OS is really a matter of emphasis. If you asked the designer of a general purpose OS "what is the worst case latency in your OS", they would probably answer "I don't know". It isn't something that they generally worry about unless it gets so long that someone important enough complains about it. If you ask an RTOS designer the same question, they can give you a definite answer.

also if you consider the memory used... then the RTOS will consume little memory & our general purpose OSs.. you know that... as the new OS release are coming out... they are occupying more memory...
yeah as you said RTOS are used in Embedded Systems... The main aim in our embedded system is that... the responce should be quick... because.. these system are used in very critical situations/applications... like in our modern cars...
If these cars encounter in an accident then immidiately in a fraction the airbags will be blown... to protect the driver... but if you use the general OS.. then.. god help them....

So If you use winXP in a camera processors with P4 3.5GH then... its okie having a latest & high speed processor... still the responce time of the OS will be the same.. in winXP.... here we just need to capture a pic in fraction of second.
there is no problem if you use different configuration for your camera... then you have to wait to capture your pic... click it & then wait forfew seconds to get the picture....
So... i think you got the Importance of RTOS over OS... :)

difference between rtos and normal os

RTOS is specially trimmed os. Most likely for uc.

difference between desktop os and rtos

Hi !!

Ok guys

Can Someone tell.

Whats the magic that RTOS is able to meet timing needs

and where it is used (specifically )

What a simple electrical engineer needs to know abt it

and who is the man .... whom Must learn RToS ???

Does RTOS run on common desktop PC ??? or some thing else????

Can someone refer a link for RTOS

A Book


desktop os versus rtos

why this kind of questions are asked and answered again and again. people can just check the old topic for answers

rtos vs gpos


1. It is time deterministic
2. High accuracy Resource allocation
3. Configurable Kernel
4. BSP support for external dependancy to another system
5. Mostly used in Embedded systems

Normal OS:

1. It may or may not be time deterministic ( Eg Hard OS is time - deterministic)
2. General level Resource allocation
3. Configurable(may or may not be) Kernel(e.g. in LINUX you can configure some application level kernel)
4. Package support is available here
5. Mostly used in general purpose systems

needs of rtos over normal os

What is RTOS?
1)A real time operating system (RTOS) is an operating system that guarantees a certain capability within a specified time constraint.
2) An OS is a system program that provides an interface between application programs and the computer system (hardware)
3) The applications where dependability that a certain task will finish before a particular deadline is just as obtaining the correct results.
4) Besides meeting deadlines RTOS must also be able to respond predictably to unpredictable events and process multiple events concurrently.
5) A system application/computer/operating system operates in real time to the degree that those of its actions which have time constraints are performed with acceptable timeliness.
6) A system is real time the degree that it employs real time resource management.The resources are explicitly managed for the purpose of operating in real time.
7) The system operating in real time needs an appropriate balance of real time resource management & hardware resource capacity.

Added after 3 minutes:

Four main tasks of OS
1)Process Management
Process creation
Process loading
Process execution control
Interaction of the process with signal events
Process monitoring
CPU allocation
Process termination
2)Interprocess Communication
Synchronization and coordination
Deadlock detection
Process Protection
Data Exchange Mechanisms
3)Memory Management
Services for file creation, deletion, reposition and protection
4)Input/Output Management
Handles requests and release subroutines for a variety of peripherals and read, write and reposition programs

Added after 2 minutes:

Real time Applications Used Today:
1) Military : For gathering data from a wide variety of real time sensors (satellite,air,surface,subsurface) and delivering it to analysis capabilities and weapon systems
2) Telecommunications: Real Time access to information from vast array of devices including computers,set top boxes,PDAs,Pagers and wireless phones.
3) Aviation: Improved real time capabilities will increase safety and efficiency by identifying dangerous situations and enabling flexible routing to relieve congestion and prevent collisions
4)Automotive : Commuters will receive real time data , GPS location information and operational data via ground stations and satellites , thus routing the driver around accidents , roadwork or traffic congestion in real time.
5) Scientific : For monitoring and instrument information is increasingly distributed on a vast scale ,enabling scientist to verify even small scale nuclear detonations as well as helping smaller remote countries prepare for weather and seismic disastors.

difference between rtos and os

No mode switching i.e no switching between user mode and kernel mode

Due to no mode switching time consuming is very less

So based on above point it is application specific

Every thing related to task


Widely used in Embedded systems

Mode switching is there through system call

Due to mode switching time consuming is more

Not application specific

Every thing is related to Process

Not like that

Used in all most all general purpose applications

example of normal os

RTOS is used in embedded systems, it is a time accurate OS, where every task must be done in prespecified time length.

But OS is process based. Generally OS runs in PCs where they have strong CPUs thus there is no timing needed, it runs process fast enough.

In an RTOS how many task (at least a ceiling of max. task number is defined before run time ), But OS has no idea about its max task number. If task number is very high in both RTOS and OS. Former will fail while second will just slow down!

rtos vs normal operating system

Whats the magic that RTOS is able to meet timing needs ?

Answer for the above is if u take Example of car, BREAKS.whenever u are pressing car breaks immediately car has to stop.if not chance of accident may occur. Here time becomes significant.this is what meeting time needs.

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