Assembly increment and loop

Question

I want to know how to display an output like this using loop and incrementation using ASCII codes.

Aa Bb Cc ... Zz

This is my working code below, and it seemss, there is / are many mistakes. It becomes an endless loop.

Please check and help me.

Thanks.

.model small
.stack 200h
.code

main proc

    mov ah, 0      
    mov al, 12h   ; Clear screen
    int 10h

    mov ah,3    
    mov bh,0     ; get cursor
    int 10h

    mov ah,2      
    mov bh,0      ;set cursor
    mov dl,12
    int 10h


    mov cx, 5      ; counter


t1:


    Mov dl, 65    ; A   
    mov ah, 2h
    int 21h

    add dl, 1


t2:

    Mov dl, 97    ; a
    mov ah, 2h
    int 21h

    add dl,1

loop t2

loop t1

    mov ah, 4ch
    mov al,00h
    int 21h



endp
end main

Answer 1

    mov cx, 5      ; counter
    Mov dl, 65    ; A   

t1:
    mov ah, 2h
    int 21h

    add dl, 32    ; 97 - 65 - convert to LC

    mov ah, 2h
    int 21h

    sub dl,31     ;remove the 32 added, but increment
    push dx       ;save DX on stack
    mov dl, 32    ;space character

    mov ah, 2h
    int 21h

    pop DX        ;return DX from stack

    loop t1

[Amended in the light of Michael's comment - Add dl,1 became sub dl,31]

(I've omitted your initialisation and termination which should be fine)

Your issues are:

t1..t2 : load DL with 'A' and output it; then increment
t2..loop t2 instruction: load DL with 'a' and output it; then increment
- do this 5 (contents of CX) times. Note you are loading DL with 'a' each time
- AND that CX will be decremented each loop, so the loop terminates when CX BECOMES 0
loop t2: Next, loop back to t1 and repeat until CX BECOMES 0.

So, at the loop t1, CX is already 0, and is thus decremented and the program loops back to t1, so A is output until CX once again becomes 0, 65534 loops later.