what is real time operating system ?

[Parth86]

I have some question ?

1) how does kernel work in operating system?
all operating system have kernel
kernel is part of operating system
It manage task of computer

2)what is real time operating system and general purpose operating system
I don't know much but I think
general purpose operating system means - operating system in computer
real time operating system - operating system in mobile phone

 

[KeepItSimpleStupid]

1) I can't answer that easily at all even though I have written an OS and have taken a course in operating systems and I programmed for an RTOS.

A general purpose OS: Windows, Mac. The whole idea is to share resources fairly.

Embedded Software (May not be an OS): Linux in a router, for instance.

RTOS - really means having a guaranteed response to an event. If a bit goes high somewhere on a port, the OS has to recognize it within a "set time". It can't wait for user input and then respond.

 

[Parth86]

I am beginner If you know some good links ,thread article suggest me where i can learn easily
my plan
1)I am searching what's the general requirement for any os?
2)what specification i need to design os?
3)which language is used ( i think java)
4)which software is used to build operating system?

 

[KeepItSimpleStupid]

I am beginner If you know some good links ,thread article suggest me where i can learn easily
my plan
1)I am searching what's the general requirement for any os?

Fairness or determinism.

2)what specification i need to design os?

See: https://en.wikipedia.org/wiki/LynxOS for an RTOS

Mine was a group project (In my case 2 instead of 4 people). We had to emulate an instruction set. Emulate reading "punch cards" and emulate "printing" the output of the jobs. It was my very first C program.

Now my first FORTRAN program took two of us about 8 months to write. It was real-time too. The FORTRAN program had a very short assembly routine. We needed the instruction, move from previous instruction space" or "data space" for some reason.

3)which language is used ( i think java)

JAVA is interpreted, so it would generally not be used for an OS. So, C or assembly. A friend an I set out to modify a commercial OS to handle "scope rubouts" We were privy to the OS sources. I designed it, he wrote it.[/quote]

4)which software is used to build operating system?

A compiler or assembler.

 

[NorthGuy]

I am beginner If you know some good links ,thread article suggest me where i can learn easily

Writing an OS is a very hard task for the beginner.

Your question sounds like this:

I'm a begginner and I want to build an airliner for 5000 seats. Where do I begin? What is the best material? I guess wood.

 

[Parth86]

real time operating system-it response in fix time
operating system - It wait for user input and then respond.

Its good for me if anyone can explain both with real example

 

[kubeek]

real time operating system-it response in fix time

by definition it doesnt need to respond after some exact time, but it has to guarantee that it will respond within some time limit.

operating system - It wait for user input and then respond.

how about reading something first? There doesnt have to be any user input whatsoever.
https://en.wikipedia.org/wiki/Operating_system

 

[KeepItSimpleStupid]

A print queue is not real time. It's sort of first come, first served.

Real-time might be as simple as if a port changed state, it will be serviced by the OS within 100 uS or it could be, if I have a process that is supposed to run once a second, it will never be more than 100 uS late.

The point is a "guaranteed" response to an event, not "fairness".

 

[Parth86]

gp operating system is not time dependent
A user can run many applications at the same time. After pressing the SAVE button of a finished document, there is no particular time limit that the doc should be saved within 5 seconds It may take several minutes (in some cases) depending upon the number of tasks and processes running in parallel

real time operating system is time dependent
ATM card user is supposed to get his money from the teller machine within 4 or 5 seconds from the moment he press the confirmation button. The card user will not wait 5 minutes at the ATM after he pressed the confirm button. So an ATM is a real time operating system

 

[Parth86]

gp operating system is not time dependent
A user can run many applications at the same time. After pressing the SAVE button of a finished document, there is no particular time limit that the doc should be saved within 5 seconds It may take several minutes (in some cases) depending upon the number of tasks and processes running in parallel

real time operating system is time dependent
ATM card user is supposed to get his money from the teller machine within 4 or 5 seconds from the moment he press the confirmation button. The card user will not wait 5 minutes at the ATM after he pressed the confirm button. So an ATM is a real time operating system

 

[KeepItSimpleStupid]

I don't lie your examples. Take a look here: https://en.wikipedia.org/wiki/Real-time_operating_system

They used an HDTV receiver as an example of an RTOS. I would use a rocket's guidance system as an example of a RTOS.

I'm having a hard time putting the ATM and even a MICROWAVE as an RTOS. Why? One task at a time. No real preemptive scheduling.

ATM
Read card
validate card
read PIN from keypad
Select function (Get money from acct x)
Get amount from keypad
Validate amount
Contact central server for balance information
Validate withdrawal
Dispense cash

We could make a windows based ATM and I think that some are. We could probably get away with a Windows microwave, but it's overkill. We could not use a Windows computer for an car Engine Control Unit.

I noticed decreased engine performance when reading values from the OBDII port. So, a car ECU is probably an RTOS because of the networking (now primarily CAN bus) and Engine Control.

 

[Parth86]

operating system that provide interface between hardware and application software
operating system - windows Linux
Example - we use operating system for computer
- we use operating system for mobile
please give other example where we used operating system ?

 

[KeepItSimpleStupid]

I'd ask why not what?

The OS is necessary because there are multiple processes and potentially shareable resources.

 

[Parth86]

I'd ask why not what?

The OS is necessary because there are multiple processes and potentially shareable resources.

i just wanted to confirm . I have another doubt . i have given three example computer, mobile and ATM
all these device used display .

so every operating system should have display ?

i am asking this because I read somewhere operating system for micros

 

[KeepItSimpleStupid]

Missile, Quadcopter, Space Probes, Satelites

Displays might be kind of hard to define, but we could call it an HMI or Human-Machine-Interface.

Not sure where these fit: http://store.irobot.com/home/index.jsp?source=AFF_IRBT&utm_source=cj&utm_medium=affiliates

Or even these: **broken link removed**

If a device is controlled by a webpage, does it have a display?

Technically no, it's not built in. It does, however use a webpage as it's HMI. The term "HMI" would cover buttons and lights too.

Even a simple power switch" is an HMI.

 

[Parth86]

simple we can store operating system in to the memory of computer
operating system that provide interface between hardware software like usb driver, LAN driver ,sound driver and application software like window media player , vlc player ,ms word

same for mobile device

If we don't use display then how can we use application software , so think the device that used operating system should have display

 

[kubeek]

Why do you think it needs to run application software? Imagine a simple web server. It has no display, it is just a pc happily running somewhere in a rack. You ask it to give you some wabe page and it sends it to you. You ask it to take care of your mail, and it does that.
Does it need to have Word and Photoshop installed? No.

On the other hand, any device should have an output to make any sense, but it doesn´t necesarily have to be a display.
A device without any sort of output is possible but pointless - imagine a pc that lets you type on the keyboard, but does absolutely nothing when you do that.

 

[NorthGuy]

A device without any sort of output is possible but pointless.

Black box on a plane?

 

[kubeek]

Black box on a plane?

I would say that it still has an output - the storage media.

 

[Parth86]

hello again , multitasking - ability to execute more then one task at same time

Q) can one processor execute two task at same time?
example - I am typing letter on ms word office and at same time I want to play audio , can i do this two task at same time in real time os if yes then which one should be executed first