NASM Forum > Programming with NASM

Example INT 0x10 AH 0x0E in Bios

(1/2) > >>

ramosaurio:
Hello everyone, i just started to learn programming with nasm. I'm doing a little program to verify the Bios interrupt set.
I have experience programming with ARM, but now i'm stuck with the 0x10 interruption. I did a simple "Hello" to print it with the 0X0E mode.

--- Code: ---[BITS 16]

org 0x7c00
mov ah, 0x0e
mov al, 'H'
int 0x10
mov al, 'E'
int 0x10
mov al, 'L'
int 0x10
int 0x10
mov al, 'O'
int 0x10

jmp $

times 510 - ($-$$) db 0
dw 0xaa55


--- End code ---

I take this example from this Bootloader project https://github.com/cfenollosa/os-tutorial/tree/master/02-bootsector-print

The problem is that when i mount it in my VM it only prints the first lettler but not the others letters. 

Thank's in advantage.

PD. I think that i post it in the correct section, sorry if there are any problem.

Frank Kotler:
Hi  ramosaurio,

Welcome to the Forum.

I would expect your code to work on real hardware. Who knows what a VM might do? Try reloading ah with 0x0E before each interrupt.

Best,
Frank

debs3759:
With a properly written IBM compatible BIOS that should work. Can you use a debugger to single step through the code while in the VM, to see if it is changing any registers?

fredericopissarra:
Try this:


--- Code: ---bits 16

  jmp   0x7c0:_start  ; I prefeer to use smaller offsets!
_start:
  push cs
  pop  ds

  cld
  lea   si,[msg]
.loop:
  mov   ah,0x0e
  lodsb
  test  al,al
  jz    _exit
  mov   bx,7      ; page 0, white foreground.
  int   0x10      ; probably int 0x10 destroys AX...
  jmp   .loop

_exit:
  hlt
  jmp   _exit

msg:  db  `Hello!!!\0`

  times 510-($-$$) db 0
  dw  0xaa55

--- End code ---

ramosaurio:

--- Quote from: Frank Kotler on February 05, 2019, 09:38:49 PM ---Hi  ramosaurio,

Welcome to the Forum.

I would expect your code to work on real hardware. Who knows what a VM might do? Try reloading ah with 0x0E before each interrupt.

Best,
Frank



--- End quote ---

I tried reloading 0X0E before each interrupt and i have the same problem.

Anyway thank's i'm going to try it on real hardware because i didn't know that the VM could give me so many problems.


--- Quote from: debs3759 on February 05, 2019, 11:21:29 PM ---With a properly written IBM compatible BIOS that should work. Can you use a debugger to single step through the code while in the VM, to see if it is changing any registers?

--- End quote ---


Okay, i'm not using any debugger for the VM, could you recommend me some free debugger? (i heard from one called IDA, but i got it and the free version doesn't support x64 architectures.

Thank's

Navigation

[0] Message Index

[#] Next page