Operating Systems

[Nick (Goodbye!)]

What coding language does Unix, Windows, and OS X use?

[dude]

Think the programmers usually code in c family languages - if I remember rightly the linux kernel is written in c. There's also some bits written in assembly and it used to be the case that all operating systems were written entirely in assembly.

[Nick (Goodbye!)]

So they use a mix of Assembly and C?

[Bob]

Aug 16, 2009 15:29:31 GMT -8 Nick (Goodbye!) said:

So they use a mix of Assembly and C?

Kernels are almost always written in C with Assembly being used for certain device interactions and strapping. Once you're above the kernel the languages begin to vary.

[Jordan]

Aug 16, 2009 16:19:41 GMT -8 Bob said:

Aug 16, 2009 15:29:31 GMT -8 Nick (Goodbye!) said:

So they use a mix of Assembly and C?

Kernels are almost always written in C with Assembly being used for certain device interactions and strapping. Once you're above the kernel the languages begin to vary.

I heard that "the core" which I took to be the kernal was usually written in assembly for better performance, and then C was gradually used. Is this a false statement? I read it on a website where this guy was developing his own OS, but I really haven't read much about them and I'm sure that the development for them is constantly changing.

[Bob]

Aug 16, 2009 19:40:24 GMT -8 Jordan said:

Aug 16, 2009 16:19:41 GMT -8 Bob said:

Kernels are almost always written in C with Assembly being used for certain device interactions and strapping. Once you're above the kernel the languages begin to vary.

I heard that "the core" which I took to be the kernal was usually written in assembly for better performance, and then C was gradually used. Is this a false statement? I read it on a website where this guy was developing his own OS, but I really haven't read much about them and I'm sure that the development for them is constantly changing.

I definitely have not gone digging around in the Linux kernel because quite frankly I don't have much interest in OS architecture. But I do know that Linux uses a relatively small amount of Assembly. Likely just what is absolutely required for architecture-specific routines. The bulk is written in C.

[Jordan]

Aug 16, 2009 20:07:16 GMT -8 Bob said:

Aug 16, 2009 19:40:24 GMT -8 Jordan said:

I heard that "the core" which I took to be the kernal was usually written in assembly for better performance, and then C was gradually used. Is this a false statement? I read it on a website where this guy was developing his own OS, but I really haven't read much about them and I'm sure that the development for them is constantly changing.

I definitely have not gone digging around in the Linux kernel because quite frankly I don't have much interest in OS architecture. But I do know that Linux uses a relatively small amount of Assembly. Likely just what is absolutely required for architecture-specific routines. The bulk is written in C.

Yeah, I'm sure these days that is true because writing assembly isn't any fun and takes forever. It would be good to know, though. They say you can write more efficient code in high level languages since you know what the compiler will be doing with it.

[BFD]

According to my professors in college (way back in the early 90's), IBM and Microsoft were doing their primary operating system development in C, then rewriting the poor performing routines in Assembly. I believe this applied primarily to OS/2 (the precursor to Windows NT, XP and beyond). I've skimmed a few operating system architecture white papers since then that indicated compiler optimization technologies have advanced to the point where a human cannot improve performance using assembly. The only place it would be used is, as Bobby Hensley indicated, architecture specific tasks.

[Nick (Goodbye!)]

Can an operating system be written in C++? Or only C?

[Jordan]

Aug 17, 2009 11:29:34 GMT -8 Nick (Goodbye!) said:

Can an operating system be written in C++? Or only C?

You don't have to use C, but C is most likely the best to use because of performance.

[«The Silver Lining»™]

Ive been thinking of making a small operating system, I was thinking of using C++ and if your going to use C++, i found a good tutorial for making C++ kernels:

www.osdever.net/tutorials/pdf/cpp_kernel.pdf

Ive always wanted to make an os in C++ since i started programming in the language. I just dont know where to start at the moment. Im carefully studing tutorials on the net.

[Nick (Goodbye!)]

Okay, thanks. That helps a lot.

[«The Silver Lining»™]

No problem