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OS Development

nick123

     I've been studying assembly language for a long long long time, and I want to try OS Development. I've heard of MikeOS it was entirely written in real mode assembly. I looked over the code of MikeOS and now I feel very discouraged. It is a lot of complicated code just for a simple os.

 

MikeOS - simple x86 assembly language operating system

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    C was originally created as a system programming language so that you could write operating system kernels and utilities using portable high-level syntax.  C was designed to be easy to compile into efficient assembly language, specifically PDP-11.  Like many people, I think of C as a portable assembly language that uses high-level notations.

     

    As an amusing historical note, I once used a Unix system where the man page for the assembler had the following text:

    Assembly language is dead.  Necrophilia will be punished.

    That said, you'll write better C programs if you've mastered assembly language first.  You'll also find it easier to debug C programs since the C run-time model is machine language, i.e., no seat belts to protect your program from itself.

     

    JMO/YMMV

  • 0 in reply to nick123

    Nick Gallagher wrote:

     

    Why  is C portable and not assembly?

    An assembly language program only runs on one computer architecture, i.e., one instruction set.  You can't run ARM assembly language on x86, or vice-versa, because the instructions and processor registers for one assembly language aren't the same as another.  (Well, you can use an emulator if you don't need high performance.)

     

    Unless it accesses implementation-specific device registers, a well-written [*] C program can run on any computer architecture for which you can get a C compiler.  So you can run the same C program on ARM and x86, except for the parts that access device registers.  If those are in device drivers, your well-written application programs are completely portable.

     

    [*]  There are some nuances that make C programs non-portable, such as writing code that depends on whether your architecture is big-endian or little-endian.  This is not an issue between x86 and ARM, because both are usually little-endian.  It is an issue porting C programs between x86/ARM and 68000/PowerPC.  There are other nuances as well, which is why software development groups need a few "grown-ups" around who have mastered assembly language so they know what things can go wrong and how to fix them.

  • 0 in reply to johnbeetem

    So, can C be compiled into flat binary like assembly? Also, is C anything like assembly. Can I put bits of assembly code in C?

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