Hello World! Program not working, plz help

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Yawgmoth

Joined: 20 Aug 2003
Posts: 37

Yawgmoth 13 Sep 2003, 21:55

When I try to compile this:

Code:

org 100h
__pause db 'Press any key to continue...$'
mov dx,msg_a
mov ah,9
int 21h
msg_a db 'Hello World',0Dh,0Ah,'$'
mov dx, __pause
mov ah, 07h
int 21h
mov ah, 07h
int 21h
mov dx,msg_b
mov ah,9
int 21h
msg_b db 'Hi again',0Dh,0Ah,'$'
mov dx, __pause
mov ah, 07h
int 21h
mov ah,4Ch
int 21h

and try to execute the .com file, it just exits w/o displaying anything.

13 Sep 2003, 21:55

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8354
Location: Kraków, Poland

Tomasz Grysztar 13 Sep 2003, 22:08

You have put data at the beginning of your program, and it gets executed before your actual code. I shouldn't have to say that this can be very dangerous. If you don't want to move your data to the end of your program, you can just skip it with jump instruction, so it won't get executed:

Code:

org 100h 
jmp start
__pause db 'Press any key to continue...$' 
start:
; and here the rest of program...

PS. Have you seen my DOS tutorial preliminary? I'm trying to clarify such things there, it's posted in this thread: http://board.flatassembler.net/topic.php?t=118.

13 Sep 2003, 22:08

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