How to write and execute PURE machine code manually without containers like EXE or ELF?

Question

I just need a hello world demo to see how machine code actually works.

Though windows\' EXE and linux\' ELF is near machine code,bu

Answer 1

Everyone knows that the application we usually wrote is run on the operating system. And managed by it.

It means that the operating system is run on the machine. So I think that is PURE machine code which you said.

So, you need to study how an operating system works.

Here is some NASM assembly code for a boot sector which can print "Hello world" in PURE.

 org
   xor ax, ax
   mov ds, ax
   mov si, msg
boot_loop:lodsb
   or al, al 
   jz go_flag   
   mov ah, 0x0E
   int 0x10
   jmp boot_loop

go_flag:
   jmp go_flag

msg   db 'hello world', 13, 10, 0

   times 510-($-$$) db 0
   db 0x55
   db 0xAA

And you can find more resources here: http://wiki.osdev.org/Main_Page.

END.

If you had installed nasm and had a floppy, You can

nasm boot.asm -f bin -o boot.bin
dd if=boot.bin of=/dev/fd0

Then, you can boot from this floppy and you will see the message. (NOTE: you should make the first boot of your computer the floppy.)

In fact, I suggest you run that code in full virtual machine, like: bochs, virtualbox etc. Because it is hard to find a machines with a floppy.

So, the steps are First, you should need to install a full virtual machine. Second, create a visual floppy by commend: bximage Third, write bin file to that visual floppy. Last, start your visual machine from that visual floppy.

NOTE: In https://wiki.osdev.org , there are some basic information about that topic.