CODEWITHSUNDEEP
assemblyx86dos
user2248734
user2248734

Reputation: 79

Printing a new line in assembly language with MS-DOS int 21h system calls

I've been trying to print a new line while also printing the alphabet using assembly language in nasmide for the past few days and can't get it, what I've tried so far has either printed nothing, printed just A or printed a multitude of symbols, Google hasn't been helpful to me so I decided to post here.

My code so far is 

CR equ 0DH
LF equ 0AH

main:
mov AH,02H
mov CX,26
mov DL, 'A'

while1:
cmp DL, 'A'
add DL, 01H
int 21H
mov DL, 0DH
mov DL, 0AH
int 21H
cmp DL, 'Z'
je Next
jmp while1

Next:
mov AH,4CH
int 21h

Upvotes: 5

Views: 121430

Answers (7)

Mosroor Mofiz Arman
Mosroor Mofiz Arman

Reputation: 1

.MODEL SMALL;Code model set to small
.STACK 100H ;Stack memory 100H size
.CODE       ;Code starts from here

START:      ;Mark start of code segment

INPUT:      ;Mark input of code segment
MOV AH, 1   ;AH=1,Single key input
INT 21H     ;Input in AL
MOV BL, AL  ;BL=AL, Input in BL

OUTPUT:     ;Mark output of code segment
MOV AH, 2   ;AH=2,Single key output
 
MOV DL, 0AH ;DL=0AH, ASCII for newline
INT 21H     ;Print DL
MOV DL, 0DH ;DL=0DH, ASCII for carriage return
INT 21H     ;Print DL

MOV DL, BL  ;DL=BL,Display the input 
INT 21H     ;Print DL


Exit:       ;Mark exit of code segment
MOV AH, 4CH ;4CH = DOS exit fuction. Handover the control to OS and exit program
INT 21H     ;Invoke the instruction for interrupt where there function needs to be executed

Upvotes: 0

CCC
CCC

Reputation: 149

Code for printing new line

MOV dl, 10
MOV ah, 02h
INT 21h
MOV dl, 13
MOV ah, 02h
INT 21h

ascii ---> 10 New Line

ascii ---> 13 Carriage Return

That is code in assembly for new line, code is inspirated with writing machine. Our professor told us the story but I'm not good at english.

Cheers :)

Upvotes: 18

Rynxel
Rynxel

Reputation: 1

Mov Ah,02
Mov dl,42
Int 21
Mov dl,0a ---> next line 
Int 21
Mov dl,43
Int 21

Output: 
B
C

Upvotes: 0

Igor Osipov
Igor Osipov

Reputation: 157

100% works.

CR equ 0DH
LF equ 0AH

main: 
    mov DL, 'A'

while1:
    mov AH,02H      ;print character
    int 21H 

    mov BL, DL      ;store the value of DL before using DL for print new line

    mov DL, 10      ;printing new line
    mov AH, 02h
    int 21h
    mov DL, 13
    mov AH, 02h
    int 21h

    mov DL, BL      ;return the value to DL

    cmp DL, 'Z'
    je exit 
    add DL, 1       ;store in DL the next character
    jmp while1

exit:
    mov AH,4CH
    int 21h

Upvotes: 4

howard howard
howard howard

Reputation: 59

you could just use the

 mov ah, 02h
 mov dl, 13
 int 21h
 mov dl, 10
 int 21h 
 ret

but declare it as a proc at the bottom of your "main endp" you can name that function newline and call it where ever you need a newline

Upvotes: 0

user6035638
user6035638

Reputation: 1

mov dl, 0a
int 21h
int 0ah

try this

Upvotes: -5

Brian Knoblauch
Brian Knoblauch

Reputation: 21409

Well, first off:

mov DL, 0DH
mov DL, 0AH
int 21H

Isn't going to do you any good. You load 0Dh into DL and then immediately overwrite it with 0Ah without ever having used the first value... You need to make your call (int 21h) on BOTH characters...

Furthermore, you're using DL for newlines overwrites the prior use for the character... You need to save and restore that value as necessary.

Upvotes: 3

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