asm code

assume CS:Code, DS:Data, SS:Stack

Code Segment
Start:
    mov ax, Data
    mov ds, ax

    mov dx, offset prompt
    mov ah, 09h
    int 21h

    mov ah, 01h
    int 21h               
    sub al, '0'          ; Convert ASCII to integer
    mov value, al     

    ; input check
    cmp al, 2
    jb fault       ; Jump if below 2
    cmp al, 5
    ja fault       ; Jump if above 5

    ; Countdown loop from 9 to 0
    mov cl, 9             ; Start countdown from 9

Countdown:
    mov dx, offset message
    mov ah, 09h
    int 21h

    ; Print current number
    mov al, cl           
    add al, '0'          ; Convert to ASCII
    mov dl, al           
    mov ah, 02h          ; Function to print character
    int 21h

    ; New line after printing number
    mov dx, offset newline
    mov ah, 09h
    int 21h

    ; delay 
    push cx              ; Save CX
    mov cx, 0FFFFh       ; Set delay count
delay:
    nop                  ; do nothing
    loop delay       	 ; Loop until CX is zero
    pop cx               ; Restore CX

    ; Decrement counter and check
    dec cl               ; Decrement CL
    jnz Countdown        ; Loop until CL is zero

End_program:
    mov ax, 4C00h
    int 21h

fault:
    mov dx, offset prompt
    mov ah, 09h
    int 21h
    jmp Start            ; Restart program

Code Ends

Data Segment
prompt      db 'Enter a number between 2 and 5: $'
value       db ?                   ; Variable to store user input
newline     db 0Dh, 0Ah, '$'      ; New line
message:    db 'Counting down: $'

Data Ends

Stack Segment
Stack Ends

	   End Start