store a number in array and display it problem

Hello guys!

I'm having difficulties storing an number in an array and displaying it on the screen. When i compile it dont have errors. But when i enter the 1st number on the screen, it just crashes. I'll post my code here for you guys to have a look.

Code:

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.model small
.stack 100h

.data
        num db 1 dup(?)        ;array to store number
        enter_number db "Please enter number from 1-7 only: $"
.code

        main proc
                mov ax,@data
                mov ds,ax

                call input

                mov ax,4c00h
                int 21h
        main endp

        input proc

                mov ah,09h
                mov dx,offset enter_number
                int 21h
               
                mov ah,0
                int 16h

                mov bx,0
                mov num[bx],al

                mov ah,0
                mov dl,num[bx]
                int 21h

        input endp
end main

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I seriously dont know what is the problem. May be i just started assembly not too long ago. Hope some 1 do show me how to code it correctly. I dont know where did i go wrong. Thanks!