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*How to create your own operating system*, Part 2.1, Hello World bootloader

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Published on Nov 13, 2012

Follow my new twitter account about Operating System Development only: http://bit.ly/Id01we (Thanks!)

Hello and welcome to my second tutorial in my how to create a operating system eerie.
In this video we will create our first bootloader which can print a message. It will also learn how to setup your developing environment.

Part1 = http://youtu.be/Lgd5aV2LKrk
Part 3 = http://youtu.be/Y8KlOAJwY6w

Website: www.osyd.tk
Take a look at my website, under the download panel you can download the source code.

Code:

bochsrc.txt:
romimage: file=BIOS-bochs-latest, address=0xF0000
vgaromimage: VGABIOS-lgpl-latest
floppya: 1_44=a:, status=inserted #If your floppy drive letter is B you have to use 1_44=b
log: OSDEV.log
error: action=report
info: action=report

boot.asm:
BITS 16 ; The mode we are running in (default for every modern computer)
ORG 0x7c00 ; the origin, the boot loader is always loaded at 7C00 by the BIOS
jmp Main ; Jump the a label called "Main"


;IN: si=string, OUT:-
Print:
lodsb ; Load string byte (Load a character that's in si into al)
cmp al, 0 ; If that character is equal to "0" jump to done
je Done




mov ah, 0eh ; Set parameters for interrupt 10
int 10h ; Call the interrupt
jmp Print ; Loop back in Print to print the next character

Done:
ret ; return back to the place we where called

Main:
mov si, msg ; Move the data of msg into si
call Print ; Call the Print label
cli
hlt ; Halt the system

msg db 'Hello World!',0 ; Define the variable msg to a string

times 510 - ($-$$) db 0 ; make sure the file is 512 bytes

dw 0xAA55 ; Last 2 bytes need to be AA55

Type in the CMD prompt:
It's important you use nasmpath.bat!
nasm -f bin boot.asm -o boot.bin
debug boot.bin
w 100 0 0 1 (This code will copy it to the A: drive, w 100 1 0 1 will copy to the B: drive)
q
exit


If you like my video's please like comment and subscribe...
Thanx for watching and see you next time guys ;)

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