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Index > OS Construction > Problem with printing text :(

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DataHunter2009



Joined: 10 Jun 2005
Posts: 144
DataHunter2009
Hello! I'm writing my first OS in FASM, but I am having problems! I am booting in to 16 bit real mode and trying to print text, but it just hangs in VMWare! (I don't have another computer to test it on yet).

Here's my code:
Code:
org 0x7C00 

use16
; START REALMODE

start:
        xor   ax,ax
        mov   ds,ax
        mov   es,ax
        mov   ss,ax
        mov   sp,0x7C00 

; TURN FLOPPY OFF

        mov   dx,3F2h
        mov   al,0
        out   dx,al

; PRINT TEXT

mov     si,HelloWorld
mov     ah,0Eh

HelloWorld  db  "Hello World!"    

Can anyone tell me what I have done wrong? Thanks! Very Happy
Post 13 Sep 2005, 00:12
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Artlav



Joined: 23 Dec 2004
Posts: 188
Location: Moscow, Russia
Artlav
And what about int 16h?
Post 13 Sep 2005, 02:44
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Matrix



Joined: 04 Sep 2004
Posts: 1171
Location: Overflow
Matrix
Code:
mov     si,HelloWorld 
mov     ah,0Eh 
.loop:
mov al,[si]
or al,al
jz .done
int 10h
inc si
jmp .loop

.done:
xor ah,ah
int 16h

HelloWorld  db  "Hello World!",0
    
Post 13 Sep 2005, 03:16
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Dex4u



Joined: 08 Feb 2005
Posts: 1601
Location: web
Dex4u
As your making a realmode OS, you should do this at the end of Matrix text code:
Code:
.done:      jmp $    


And you only need the turn off floppy if your going to pmode.
Post 13 Sep 2005, 12:56
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DataHunter2009



Joined: 10 Jun 2005
Posts: 144
DataHunter2009
Thanks! That works! How would I go about printing more than one line?
Post 13 Sep 2005, 20:56
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Dex4u



Joined: 08 Feb 2005
Posts: 1601
Location: web
Dex4u
You could do some thing like this:
Code:
org 0x7C00 use16; START REALMODEstart:xor   ax,axmov   ds,axmov   es,axmov   ss,axmov   sp,0x7C00 ; PRINT TEXT FIRST MSGmov   si,HelloWorld1 mov   ah,0Eh call  print; PRINT TEXT SECOND MSGmov   si,HelloWorld2 mov   ah,0Eh call   printjmp   $;PRINTprint:.loop:mov al,[si]or al,aljz .doneint 10hinc sijmp .loop.done:ret;DATAHelloWorld1  db  "Hello World1",10,13,0HelloWorld2  db  "Hello World2",10,13,0    
Post 14 Sep 2005, 09:31
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DataHunter2009



Joined: 10 Jun 2005
Posts: 144
DataHunter2009
Thanks! It works great! This helped me out alot Very Happy
Post 14 Sep 2005, 20:54
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