How to work this code with zero/0 ?
; this program asks the user to enter two numbers, and decides whether ; the first or the second entered number is bigger.
.model small
.stack
.data
text1 db 'Enter first number: $'
text2 db 'Enter second number: $'
text3 db 'First is bigger.',10,13,'$'
text4 db 'Second is bigger.',10,13,'$'
text5 db 'Equal numbers.',10,13,'$'
new_line db 10, 13, '$'
.code
start:
mov ax, _data ; ds - data segment
mov ds, ax
mov ax, 3 ; clear screen
int 10h
mov ah, 9 ; text1 to screen
lea dx, text1
int 21h
mov ah, 1 ; read char
int 21h
push ax ; char to stack
mov ah, 9 ; jump to the start of the next line
lea dx, new_line
int 21h
mov ah, 9 ; text2 to screen
lea dx, text2
int 21h
mov ah, 1 ; read char
int 21h
push ax ; second char to stack
mov ah, 9 ; jump to the start of the next line
lea dx, new_line
int 21h
pop cx ; second char from stack to cx
pop bx ; first char from stack to bx
cmp bx,cx ; compare chars
je lab_equal
cmp bx,cx ; compare chars
jg lab_first
mov ah, 9 ; text4 to screen
lea dx, text4
int 21h
jmp vege
lab_equal:
mov ah, 9 ; text 5 to screen
lea dx, text5
int 21h
jmp vege
lab_first:
mov ah, 9 ; text3 to screen
lea dx, text3
int 21h
vege:
mov ax,4c00h ; exit
int 21h
end start