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 Hello world, need some help 
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Joined: Sat Jan 16, 2010 11:38 am
Posts: 2
Post Hello world, need some help
Hi, i'm new in this of OS Dev and I need some help with my bootloader.

Code:
[BITS 16]
[ORG 0x7C00]

mov si,msg
call printf
jmp $

putc:
  mov ah,0x0E ;bios function to write a char on the screen
  mov bh,0x00 ;page number,0
  mov bl,0x07 ;white text on black background
  mov al,[si] ;writing the char from the si register
  int 0x10 ; calling video
ret

printf:
  nextc:
  or si,si
  jz exitf
  call putc
  inc si
  jmp nextc
  exitf:
ret


;Data here
msg db "Hello World",10,0

times 510-($-$$) db 0   ; Fill the rest with zeros
dw 0xAA55      ; Boot loader signature


The problem is that the bootloader writes something(that i can't see) and next what I see is the cursor in the lower right corner.


Sat Jan 16, 2010 11:46 am
Profile
Post Re: Hello world, need some help
Code:
  or si,si
  jz exitf

no good
Code:
mov dh,[si]
test dh,dh
jz exitf

should be fine.


Thu Feb 04, 2010 9:47 pm
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