Numeric or Not

.model small
.stack 100h
.data
msg1 db 'Enter a number : $'
msg2 db 0ah,0dh,'Numeric$'
msg3 db 0ah,0dh,'Not numeric$'
.code
main proc
    mov ax,@data
    mov ds,ax

    mov ah,9
    lea dx,msg1
    int 21h

    mov ah,1
    int 21h
    mov bl,al

    cmp bl,48
    jl a
    cmp bl,57
    jg a


    mov ah,9
    lea dx,msg2
    int 21h
    jmp exit



    a:
    mov ah,9
    lea dx,msg3
    int 21h



    exit:
    mov ah,4ch
    int 21h
    main endp
end main